I don't think there are any "Windows 7" games like there were "Windows Vista" games like Halo 2. Generally, games are made for XP at a minimum, and they work just fine on Vista and 7 as well, with perhaps some extra tweaks for the newer OSes.
As for FPS games, come on. It's the PC. 75% of the stock in stores for the PC will be nothing but FPS games. You can throw a stone in any direction and hit about ten FPS games that are highly regarded for the PC.
Go to GameSpot, go to the PC section and filter by FPS. Or Amazon. Or any other store that sells PC games. There ya go.
Also, I heard from a little birdie that this little game called Call of Duty: Modern Warfare 2 might have come out sometime recently...