Running Win7 Professional 64-bit on a rig with a 3.4ghz Core 2 Quad, 8GB of DDR2 RAM and a GTX 285 2GB VRAM model. It's awesome, plain and simple. The Aero interface doesn't play nice with 3ds Max 2008, so I have it switched off for now.
Pretty decent rig, the graphics card isn't too great, I wouldn't buy a quadro next time, if your making stuff for gamer cards, why wouldn't you use one yourself? You'll see a greater performance difference with more ram and if you use 64bit apps.