In the past performance was important. But its becoming not so for me. I remember when overclocking used to make a huge difference to how the pc felt.
But now windows is snappy if i'm overclocked or not. Now I can run a webserver, 2 database servers,listen to mp3's, fold, prime, an IDE, a web browser with 10 tabs open, firewall, anti-virus, voice chat and write this and I don't have to make a cuppa waiting for stuff to happen anymore.
Now my e-penis is fast enough (until more bloat comes along) I want it to be quieter so instead of getting a new mobo/cpu my next upgrade will be to water.
Not smaller though.. nothing quite like a big black silent tower that can kick start the pets evolution.