Problem installing new video card

I have a Compaq SFF Deskpro EN (ENS/P866/15e/6/128c US) system with a integrated Intel 3D DVM video. I am trying to install a new Sapphire Radeon 9200se PCI video card, but after installing and rebooting the PC will not boot up, not even to BIOS setup.
Its running WXP SP2, I have tried uninstalling the Intel s/w and still wont recognize the card.
Have also tried disabling the device, but still freezes up on boot.
What am I missing????
Jerry