Windows will load a generic driver to your machine that will let you see what’s going on, but you will not be able to operate your computer at full capacity until you get the Compaq drivers, that what I assume you need.
To get the current graphics diver for your older computer, go to the Compaq website, support downloads section. If the site lets you, enter the serial number and model number of your computer. The websit3e should be able to give you a list of all the drivers that your computer came with, and the most recent updates for those drivers. Download the files to your desktop and double click on them. They are self extracting.