We dont know anything about vista though, i'm wanting to upgrade for the basic version, cause who the heck needs aeroglass anyway? Another thing is that new sound driver thing they are implementing, I dont know the details but its about being able to customize per app or something. More than likely they overhauled the looks as usual with a hint of zazz and a few new features.
The M$'s vista only thing does annoy me, they really think they can make a profit my releasing Halo2 for vista only, pfft.
Making GOW for vista only would require extra work and money because the unreal engine is already designed to work on linux? mac? ps3? xbox? so really it might not happen. Besides every linux fan will be PO'd and eventually people will pirate it because of M$ being a jerk and being happy with an older OS. But more than likely they will make every dx10 game vista only cause they want $$$ but not happy people.
those are my 7 cents