I have just purchased a Diamond Radeon HD 5750. I cannot for the life of me to get it to work. Every time i uninstall the current video card and restart, it just re-installs some crap video card that is installed within the motherboard. The crap it installs is called Intel(R) 82945G Express Chipset Controller 0 (Microsoft Corporation-WDDM). Im pretty sure I put the graphic card in right and connected my cables to it correctly. If it helps, I have a HP Pavilion a6120n (Vista) PC. And I did have Nvidia 8800 before. I forgot to uninstall it before I connected the new graphic card, but I did uninstall it after I realized my mistake and restarted.
rolli59 is right, you need to disable the integrated video card, and it will always install the intel chipset driver. That chipset is built into the motherboard and it won't hurt anything so just let it install it.