There's no real way to back up installed drivers. You have to back up the installation program for the drivers.
I've never heard of Nexar, but assuming they're still in business, their website is probably the best place to look for drivers. Same goes for Compaq systems, though generally speaking the best thing to do with those is take them out back and put a bullet in them to finish what nature intended.
I am looking for VGA drivers for a Nexar computer and also for the older Compaq desktoop model.
Also, where on the computer can you locate the folder with drivers so I can back them up to avoid this problem in the future?