Re: axiom 25
Essentially, MIDI is just a series of numbers. Control numbers sending note data, velocity (volume data) and channel data. So any programme that interprets these numbers can also output sound provided that they have the right sound set built in. I use Max/MSP for most of my MIDI fiddling (and Logic as DAW software). Max/MSP is actually a graphical programming interface and quite advanced, but it is very flexible, but also very complicated to beginners. Reason is a great bit of software, but not one I use.
If you want to get into MIDI synthesis, I suggest looking at Reason, but also at Ableton Live and if you want to get your hands dirty into the more complicated aspects (and believe me, it can be VERY frustrating) then Max/MSP is incredibly powerful. Most DAW packages have built in sequencers and MIDI interfaces as well that can be powerful. I use Logic Studio 8 (only works on Macs) and I have in the past used Cubase which I am not particularly fond of but is also quite powerful. Sonar 8 is another option, as is the new Pro Tools 8 - which has MIDI capability.
In short, MIDI sends data into the computer as a series of numbers, which are then received by the software. These numbers can be used to trigger sounds (which are separate from the MIDI itself and can be changed) and also mapped to control various parameters within the software. It can be complicated, but it is just numbers.
MIDI input -----> Software Interpretation ----> MIDI Soundset/Control (based on the HDD) ----> Audio Output.
There is more to it than that, but you have to remember that the control data and the sounds are entirely separate.
On that interface, the keyboard obviously inputs the note data (unless you map it separately) and the dials and knobs at the top can be mapped to control other functions, eg. volume, EQ, filter control and all sorts which can be custom-assigned.