You uninstall it, in safe mode, so your screen does not black out post of uninstalling. Then what you do is, Shut down your system. After, Unplug everything (cables to monitor). Then put in your graphic card. After that, put the cables back again. If there is nothing wrong, it should boot normally like how windows 7 should boot, But you will see as a lower resolution. What you do in this time is install your graphics driver, From the CD, From AMD website or from a pen-drive or hard drive (don't do anything in this step except this!). Then restart, and see what happens, you should be able to see the upgrade.