If you have a mic and an amp you could try that.
I've been using the mic plugin with the 1/4 to 1/8 adaptor.
I tried sound recorder (Win) first but couldn't get any sound, even though i could hear my Bass thru the speakers.
Audacity works great for me since I don't have an amp yet.
couple things I had to do:
1:down by the clock in windows is the main volume control, I had to turn Line-In all the way up (this was before I realized tyhe woofer master volume was pretty low, but it also helps get sound to Audacity)
2:In Audacity choose line in from the drop down menu
3:In Audacity, still the noise level is low, I have to amplify every recording, I usually don't do it max because the sound comes out flatter when playing back the MP3 or WAV than it sounds in Audacity. So I've been boosting the Equalization a bit too, if you amplify it too much you won't leave room for equalization.
(I suppose you could equalize first, but it's soo quiet before amplifing it)
Even with low quality recordings it's been great for me, I've just been playing around alot trying to come up with lines, I'd forget them withint a few days if I don't keep rehashing them, when I play back a recorded line it comes right back (most of the time)