I use guitar tracks pro for that. It’s probably overkill but with that software, you can tell it what “channel” of your soundcard to record. ie. microphone/line in/wav/etc. I’m sure there is a lighter application that will do the same thing out there.
edit: try this? http://www.blazemp.com/wav_recorder_software.htm
edit 2: stop posting threads to distract me from the 4 exams I have next week you assblaster