Taking off from what others have already said:
I think strippers or starting right in with sanding should be avoided. Sure, you can polish out a lot of the damage they would create, but it's a tough job, and why make extra work for yourself.
I'd try Goof Off first. (Don't use Goo Gone, that's petroleum based. Goof Off is water/citrus based. Don't breathe the fumes or get it on your skin, though. It's supposedly toxic!) Spray it on and let it soak. Hopefully it will soften up the paint. Then go at it with a plastic putty knife and see if you can scrape most of the paint off, get it down to a super thin layer.
Then try a
very light, slow sanding with a fine grit paper, moving to finer grits the thinner the paint gets, ending up with coarser then finer grades of steel wool. When you get to the 0000 grade wool, you will actually be starting to polish the acrylic itself.
Then do a final polishing & cleaning with the Novus polishes: 1, 2, and if you have heavy scratches, 3.
It might take a long, long, time, but the more time you take, the more patience you have with the stripping part, the better and smoother the polishing part will go.
You might also look in the yellow pages for a store near you that sells acrylic. They might be able to give you advice. Lots of those places do polishing, too. Maybe you could even pay them to do the whole job!
Good luck. Let us know how it comes out.
Also see these links for more info on polishing Vistas:
http://www.griptoad.com/SCRATCH.htm
http://www.griptoad.com/RESTORATION.htm