Hi cass27. The usual method of updating video drivers is as follows.
First download the new driver to your desktop. This is an exe file and will just sit there waiting for your next move.
Next go to Control Panel and use Add or Remove Programs. Remove any drivers. WDD is Windows Display Drivers. I don't know why you have the XP Display Drivers as well, I only have the one. When you remove the drivers, Windows will use the default VGA driver and you will have a very low resolution screen with only 256 colours.
Reboot the computer, don't let Windows find the driver for new hardware detected.
Double-click on the exe file you put on your desktop. This should start the new driver installation. When the installation is complte Windows should find the new driver for your graphics card, but you should be prompted on what to do at each stage.
You don't say where you downloaded your new driver from, but it is generally recommended that you download from the card makers site rather than the chip maker (Nvidia)