I wouldn't use a computer mic (or any mic). Just shoot direct into the mic input and listen to yourself through the speakers. I have my stereo system hooked into my computer speaker output.. Beats those 3" woofers on the computer speakers. You just have to watch the input levels - can get a bit noisy when too high. I mainly record mono wav files, as straight mp3 takes up too much file space, and is really unecessary if you're just recording your guitar. Anyone interested, you can give a listen to my wavs here - http://guitar-wav.com. All the wavs are recorded by the means I describe.
-Bob