According to a friend, Goldwave has a good anti-hiss filter which'll remove some of the crap. A computer is a VERY bad environment for audio since all the multi-MHz clock stuff is basically a high-frequency noise generator!

If you've got a PC with an "all-in-one" motherboard which does your sound, consider buying a new soundcard. The playback is generally OK, but recording is often appalling (mine was dreadful and added loads of extra noise) - besides, soundcards are dirt cheap these days. This also moves the audio stuff a bit away from the mobo which can't hurt.

The ideal solution would be an external A-to-D to sample the audio so that it's not affected by the computer noise. I've not seen any at any reasonable price though - you're talking pro kit here.

Grab.