I just built nearly the same system, but with a 1.2Ghz CPU, and:
30Gb IBM 75GXP
ASUS V8200 GeForce 3
Hitachi CM772 19" Monitor
I'm using a Themosonic "ThermoEngine" V60-4210 heatsink which has a 4500rpm(ie: quiet) fan. I even installed it with the standard thermal conductive pad - it seems to do the job, the Asus Probe utility reports CPU temp at 40-43ºC(105ºF) usually.

Maybe those three 80mm fans in the case help a bit, too.
[ 08-01-2001: Message edited by: juzz ]