I picked up an M-Audio Audiophile 24/96 PCI sound card on eBay last week for £15. I'm no audio snob, but in my opinion it sounds better than the onboard sound (especially as the onboard audio has a load of noise in it whenever I have CPU nap mode turned on). The main attraction of this card is that it can sample at 24-bit 96 kHz audio, so maybe I'll finally get around to digitizing my collection of 12" singles. I was a bit worried it wouldn't work as people would frequently complain about buggy drivers for this card back in the day, but I figured that I could always resell it (these cards usually run around £25 - £30 so I got a great deal!). The only downside for me is that it doesn't work with the volume keys on the keyboard, but I run the audio into a small mixer on my desk anyway so I'm not too bothered. To cut a long story short, I'm really happy with this card - it solves the noisy audio problem I had and enables me to make really good quality recordings for a very low price.