infectd

I just got a new ATI Radeon 9600xt 128mb.
To replace my HIS Radeon 9600 256mb becasue it was crap.

Now Im having similar but even mroe probs.. I actually have the card not properly seated to have it work best.. I get little pixel lines on the screen and sometimes my machine will jsut go blank and then start going to some crazy fucked up screens.. I took the second monitor of and same thing.. Should I try older driver versions or what defective card ? any help much apreciated.