Bad video

I’m having a problem with video on my WinXP professional computer. Any video i try to play is waaaay off center. It doesnt matter if i use media player, quick time, real player, etc… i’m only able to see about 1/4 of the picture. I’ve downloaded divx, still the same. i had the same problem on a winME computer, but i just updated the media player and it worked fine. I’m thinking it might be my video card… Any suggestions before i go out and buy a new one?