In my experience the worst things about using a PC for media playback are:
1. The fan noise.
2. The optical drive noise.
3. The hard drive noise.
and way down the list
4. The quality of the internal soundcard.
Solution: turn the music up a little more. Seriously. I can not hear my pc from 8' away and this is with a stock cpu fan. Once the music is playing, its a non - issue
Now, if I were using an Intel CPU with stock fan, that might be another story, though nothing a $40 tower cooler with a quiet 12 cm fan could not solve.