first, its highly unlikely any game will actually break Windows 7 , as mentioned previously , the NT based systems are solid.
in regards to games actually working, that depends not just on Windows 7 (and Im assuming you mean 64bit) , but also on other things such as drivers.
its not even necessarily a specific year or OS , Tiberian Sun for instance works fine on Win7 , while Max Payne1 and 2 had issues even starting. on my AMD 6870 (and Ive heard Nvidia cards didn't have that issue).
likewise quite a few 2D games from the late 90s won't look right without some sort of modification , one example being Starcraft , which without the right fixes has distorted colours making the game almost unplayable.
however you are very much likely to get games to work if they have one or more of these features
1)designed to be compatible with NT4.0/2000 (sometimes it doesn't even say it on the box, but it helps).
2) is a DX8 or 9 game, those generally work better with newer drivers.
3) of course, if there are fan fixes and patches for the game, some games might have fanmade installers since the official installers fail to run on a 64bit OS, NFSIII being one example.
if you want to run older games on newer hardware though , it might be useful to dual boot a copy of WinXP on the PC, most new hardware still has support for WindowsXP (apart from things like DX11 support, but older games don't need that of course) , and alot of the compatibility issues will disappear.