1) Completely remove/uninstall the previous graphics card/drivers & software. Usually this only requires using Windows Unistall app. However Nvidia & ATi offer driver removal tools.
2) Reboot, remove the old card, install new card & startup.
3) Windows will detect the hardware change, just cancel these and then use the GFX Card's supplied disc to install the required drivers & software.
As for keeping your card updated, if your card is relatively new then it should support the currently available games, so it shouldn't present a problem. However, sometimes bug & compatibility issues are fixed but you can always ask a friend to download the fix package (exe) to a USB stick etc and then you can install it.
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