Playing the Benchmark Game: Core i7 and ATI Tested in 8 Windows OS
 

So, who’s the winner? Well, if you’ve scrolled to skip past the graphs, every single benchmark has a unique operating system that does best. Overall, the two most solid performers are Server 2008 32 and Vista 32. Both of these are at the top for the 3D benchmarks, and fare okay in the 2D benchmarks as well. Deserving of flak in every day usage or not, in benchmarks, Vista 32 performs very well. Contrary to popular belief, XP and 7’s supposed “lightness” does not really translate in benchmarks. In fact, the more CPU-centric a benchmark is, the worse 7 tends to do. The only thing XP remains good for are 2D benchmarks, falling far behind the pack in all things 3D.

http://www.overclockers.com/windows-...-6-benchmarks/

The author doesn't mention this, but I should note that it's of crucial importance: CPU and Video card used.

Core 2 Duo perform better for Wprime under Vista, do better in other 2D benches under XP. While K8 seems to be better in XP for Wprime;

Single (none CF/SLI) 3D benchmarks are also better under XP, the author only tested two ATI cards in CF, we already know that multiGPU performs better under Vista/7 than under XP. Single GPU however do better under XP. And there's a difference between NVIDIA and ATI, also, of course.

so these numbers are only applicable if you bench Core i7 AND ATI video cards in CF; for all other hardware configs, you'll have to experiment yourself.

if , however, you are a sane user who appreciates functionality and stability over 0.150ms lower time in SuperPi... you can just skip the whole article ;)