Windows 7 - does game compatibility depend mostly on hardware?

i see so many people having problems with games that i'm not experiencing, so i'm wondering if compatibility is more hardware based?

gta iv, left 4 dead, unreal tournament 3... i just install them and they play. no compatibility mode or anything. but others struggle to get them to work. i guess i had problems with bioshock, but i got it working eventually...

i don't understand!

Builds less than the RC going back (like around 7022), you had to install GTA IV in Vista compatibility mode....stuff like that.

As we approached the RC, compatibility got better so that wasn't necessary any longer. Build 7127 now has the greatest game compatibility we've seen on 7, yet.

So M$ is doing well it seems.

I agree with torrentg we have seen a great increase in compatibility on both platforms x86 and x64. Most of the things I've seen is from x64 since a good bit of these games where not written to run on it, but they have made huge steps into getting them to work. By the time Windows 7 is full version game companies will have a great compatibility with x64 and patches for their older games to fix any issues they find.