My computer's unstable!

ever since I got a new graphics card, an ATI against everything I believe in, my computer’s really unstable. Opera crashes at least 2 times/hour and vlc does the same.

Also after I updated the drivers, the shadow on the windows “welcome” at boot is red. A lot of colors are just messed up, the colors in Opera too.

I had a nvidia card before, and I haven’t reformatted before I got the ATI card so I’m thinking that might have something to do with it.

Does anyone have a clue?