Video Display is messed up after an upgrade

[daw442]

I have a powermac g4 400mhz sawtooth system with 1gb ram. The system was running fine and I decided to upgrade the original video card. I purchased a used ati rage 6 agp card with 32mb. I began re-installing os x tiger. The picture looked good with no problems on disc 1. After reboot the picture was no longer good. I now have vertical lines and black and white checker squares. Any advice on what the problem is would be greatly appreciated. Thanks