I have an Acer Aspire 4920G laptop which fully supports Vista and 7.
So I install Windows 7 without any problem. I can use the aero mode and all the eye candy in Windows 7.

But when i play any games like CS, Battle Field, FIFA, Winning, etc. i cant get it to play full screen at all. I have tried to change the setting in the game the aspect ratio of the game as well but nothing seems to work. The aspect ration I get is I think 4:3 and the sides are blacked out.

Please anybody got a suggestion on how to get it to play in fulll screen?

You don't say if it was able to do full-screen running under Vista or something else. It may depend on the resolution of your screen. On my old laptop, the screen was closer to square (I think it was 1440x1280) and I had no problem getting stuff to go full screen. My new laptop has a screen that is more rectangular (1330x768) and some things can't adjust that much. If some of the games have forums, you might be able to get some additional info there.