recording on the PC shouldn't produce crappy sound, unless you are doing something bad. that is, of course, unless your computer is like a 1993 Macintosh, or something.

With electric guitar, you'll have to watch the volume, and where you put your mic (could even be a computer mic, thats what i use), because you can get a real ****ty feedback sound. But! if you work with it, there is no better way to learn. By the way, if you think your rhythms sound like **** on the computer, you should examine them more carefully, maybe its your rhythm playing that is sounding like that?

I think Cyber Fret might have some recordings you can solo over, im not sure.