This is what got me into silencing pcs. As i couldn't hear what I was doing with the sounds at the time because the computer noise was all over. Something had to be done and after a while the silencing buisness took more of my time than music producing. I had done a shit load of misstakes that I learnt from before i eventually found spcr. After doing all the homework I aslo registered...
I've also built silent pcs for other music producers. Latest was 6 months ago and a really nice low power AMD690 system with modded NSK case for this guy:
He does all the summing on a proper desk tho and he doesn't bring it on live sets (which considered to be really excellent btw)
New higher performance quad core system soon coming up for a music engineer-friend of mine.