Here's the first issue I found (only been evaluating for about 10 minutes now):

Under Render Settings and then Preview, I get a "Hardware Shading Not Supported Message" 
This is not an issue on an almost identical system running WinXP SP2.

Rendering time seems to be about the same on a simple 1 figure, 3 light setup.

System:  Asus P4C800E Deluxe Mobo
3.0 GHz P4
nVidia GeForce FX 5900 Ultra Video Card
2 Gig Ram.