(Preface: I have a bachelor's degree in electrical engineering, a master's degree in computer science, and I have been a professional software developer for over 20 years. So, I know something about this stuff. However, due to the vast variety of options available, you may have had a different experience than me.)
Funny, I too have HP dv7. But mine has quad i7, not AMD. I like it a lot. However, my one big complaint is that it does not have firewire, and there is no way to get firewire on it. A lot of good recording interfaces use firewire (like, the one that I had which is now essentially a paperweight). Let me anticipate some responses:
1. "You can get a USB to firewire adapter" - sort of, maybe, but they don't really work, especially for recording interfaces.
2. "Just get a USB audio interface" - I did. However, generally speaking firewire is ever-so-slightly superior. Because of the difference in architectures, USB is more prone to 'interference' (delays, latency, drops, etc.) from other software than firewire is. Firewire is a bit more consistent and reliable. I know there are multiple different versions of both, but all firewire throughput is more consistent than USB, which is far more important to recording.
3. "Lots of newer PC's don't have firewire" - Yes, no argument here. The next PC I buy will have thunderbolt. And then will begin the search for a good thunderbolt audio interface, ugh.
The good news is that computer technology today is so vastly superior to what it was ~10 years ago, that almost any decent computer will do. I run multiple web servers, multiple databases, multiple browsers, a few different remote desktop sessions, etc. and my machine runs just fine. That was unthinkable 10 years ago. For recording, Macs seem to be better. But that is due to the fact that all Macs and their operating system, come from one company (which has relatively high performance standards), so the situation is simpler. The variety of PC hardware is what MIGHT cause problems. Some people get lucky buy a PC, plug it in, and everything works. Of course, Macs are more expensive. I never recommend one over the other. I always tell people, you have decide how much you want to spend, and how capable are you at problem solving. Couple other random thoughts:
1. RAM is uber-important. I always try to get as much as I can afford. 2GB is really anemic today. 4GB is okay, 8GB makes everything nice.
2. For recording, hard disk performance is important. Specifically, try to get at least 7200 RPM disk (not a problem today). 10,000 RPM would be better. An SSD would be way better, but of course, way more expensive.
3. I have usually found over 20 years of buying computers, that you pay a high premium for getting the top of the line processor. If you take one step down (usually in clock speed), you can get a significant price break for something that is almost as good.
I have a Presonus AudioBox1818VSL. I like it. Number of inputs/outputs, instrument/mic/line inputs, and included Studio One DAW make it a great value. But latency interferes with how I would like to use it. My research tells me that no other USB or firewire device would be much better in that regard. However, it might not be an issue for you.
I have a 15" 2009 MacBook Pro, with a 2.53 Intel Core Duo 2. 8GB of RAM and a 500GB old-fashioned 5400 HDD. I rarely record more than six tracks at once, so the slower HDD is not an issue and improves the battery life - which is paramount to me. An SSD would be the next upgrade on the cards. My interface is an odd one - a Line 6 TonePort UX8, it was relatively inexpensive and the I/O on it is great - 8in, 8out and the latency is low, even when using all of the I/O (which has happened for live purposes once or twice).
My DAW is Reaper 64 and I'm very happy with it, as a long-time user of Logic I fancied a change and Reaper was very inexpensive and powerful. So far, I'm happy with the switch (about a year in). I also use Max/MSP a lot (5 - can't afford or need to upgrade to 6).
I like Macs and I love OS X but whether or not it's something that would work for you is entirely your choice. Try out all of the OS options if you can (and have a go on a couple of Linux distros, some of them are very easy to use and flexible with decent software support) and make your own mind up. I've had Macs since 2006 and think the hardware is great - even if it is a little more expensive. I still use my 2006 iMac casually for some audio work although the RAM (2GB) limits things a little.
I have a degree in Music Technology (Lancaster, 2008-2011) and record music in my own time. I have a lot of experience and knowledge but I'm not a professional audio engineer. I am a computer enthusiast but not a software or computing expert (though I do program on occasion in my spare time).
I find BacteriumFendYoke's response very encouraging, specifically he gets low latency with multi-channel input recording, and no problem with a 5400 HDD. Although, I would caution that most DAW vendors specifically recommend at least a 7200 HDD. Usually, they even recommend higher-speeds or multiple drives.
I am a big fan of Linux (I'm using Linuxmint right now), and I definitely recommend it for anyone who can. The problem is, many of us can't. My (software development) clients require me to work in a Windows environment, so my main machine is Windows 7. I find many people have similar restrictions. Lots of small business people need Quickbooks (no linux support). Also, many people need to work with others who use MS-Office tools. Although I've been using Libre Office (supported on all platforms) successfully, it does require a little extra effort that novices find intimidating. For many people, once you are required to make a significant investment in a platform (e.g. Windows), why would you make another significant investment in another platform? In short, I would definitely recommend anyone who has the knowledge/skills, can afford the time and effort, and has the 'freedom' to buy a no-OS laptop an install linux. The freedom, flexibility, security and community support are outstanding, and you will save lots of money over the long term. I say "lots" of money because, besides not paying for Windows or Mac-OS, you will find their are lots of high-quality applications (e.g. Reaper, Libre Office, Gimp, etc. ) for many disciplines that are either free, or much lower cost than their Windows/Mac alternatives.
I wouldn't necessarily recommend a 5400 RPM drive to others but in my case I specifically shopped for one when I replaced the original HDD because of the slight battery life advantage. My interface offers direct monitoring which helps mitigate any major latency issues. In fact, I've never had any issues with latency on either of my main recording setups (including the old iMac) but it is definitely something to be wary of.
As for the Linux question - yes. I'm a fan too. The only major issue to check that there are drivers available for your interface. I doubt mine would work in Linux (at least with the vendor's drivers - no idea if replacements are available). Do you know if there is an ASIO4ALL equivalent for Linux?
Part of the reason I like Reaper is the fact that it is cross-platform. It's a very good DAW and I've been recommending it for a long time.
I saw "Reaper" and assumed Linux (I've read about a lot people using Reaper on Linux and didn't realize it was available on other platforms as well), my mistake.
Don't know about ASIO for Linux, but I seem to recall reading that many devices were supported either through third party drivers or JACK or something. But, yes, checking for compatibility of your particular interface is absolutely critical.
Regarding battery life, it has never been a big issue for me, because I am a big poweruser (power pig?), so 99% of the time, I just insist that I'm plugged in anyway.
I'm currently using a Presonus Audiobox 1818VSL.
1. Good preamps/converters and lots of them for the price.
2. Line, mic AND instrument inputs, i.e. no need for DI.
3. Presonus's included Studio One Artist is a serious useable DAW with good support. Other companies' (e.g. Cubase, ProTools, etc.) "LE" editions are usually fairly crippled and nagging and offer crappy, if any, support. They want you to pay for "real" versions.
1. No Linux support of any kind. Presonus does not and will not (I've conversed with them about this) provide Linux drivers, nor will they publish any kind of API or specs to allow anyone else to write such drivers. As much as I like my current setup, when I buy my next interface, I will have to give this some serious contemplation.
Yes, "direct monitoring" pretty much eliminates most issues. In the case of the Presonus Audiobox series, they have a kind of 'semi-direct' monitoring. It's lower latency than a regular USB to DAW and back round trip, but it is not exactly direct either.
My issue with latency is that I would like to use some DAW plugins as real-time effects, and that is pretty much impossible, with any USB or firewire system. Perhaps my expectations were too high, but I'm still disappointed. Modern computers can easily handle the processing load, but USB and firewire just weren't designed to deliver real-time audio. I hope that changes with thunderbolt.
I built my computer for light gaming and audio recording, and it does great for like $700(I bought the parts on Black Friday). But mine has an i5 3570, ASRock Pro-4, 8GB G.Skill 1600MHz Ram, Radeon 7770, a 500GB Velociraptor 10k Drive, then 2 500GB HHDs. It out performs my dads Elitebook Workstation. Its around 3x the price. Love the thing.