First find out which company made your graphics card, look on the box or ask someone to find out, then go to the official site and download the newest graphics drivers available. At this point your going to want to set up a restore point incase something goes wrong, click the start button and go to "Help and support" then click "Undo changes to your computer with System Restore" and create the restore point. Now uninstall the current graphics drivers you are using in Control panel/Add or remove programs, restart your computer. You will notice that you are running at a low resolution and graphics load slow after that, this is normal. Now disable your firewall and install the new graphics drivers, then restart again. Now your graphics will run superb but you have to check one thing, go to your System properties/Hardware/Device manager, you should see a Display adapters device, if there is more then one display adapter in it you should disable the one you don't want. Now games and everything should run good.
Links
NVIDIA driver page
ATI/AMD driver page
Intel graphics driver page
SiS driver page
