Been playing around with pearpc for a few weeks now.
PearPC 0.3.1 (example config used) only changed to 1024x786x32 installed Mac OSX 10.3 on a 3gb image runs quite fast :) only thing not tested is networking.
Dual Intel Xeon 3.06Ghz HT
1Gb Corsair Twin XMS PC3700 ( Lat 2-2-2-5 )
2x 74Gb Raptors