Which is a better graphics card?

I need a new graphics card because when i play games on my pc (even games from like 1999) the video gets really laggy. I want to go buy a new one from BestBuy called: PNY - GeForce 6200 256MB AGP Graphics Card. The problem is that since it's $35 I dont know if its worse than the one i currently have: Radeon 7000 (came stock with my Compaq Presario 8000) I need your help to find out if i should buy it. Please help!