HP/Compaq wont have a driver
for it because Intel never made one. Here is what Intel has to say about the 865G chipset, http://downloadcenter.intel.com/Deta...adType=Drivers
The best you're going to get for that old chipset is the last XP driver.
Here are the important specs for that model,
You didn't specify which of the three versions that model of Compaq came in. One has nothing but PCI slots, one will take a low profile AGP card, and one will take a regular size AGP card. If yours is one of the ones with an AGP slot in it about the cheapest Windows 7 compatible card for it would be something like this, Newegg.com - ECS N6200A-512DZ-H GeForce 6200 512MB 64-bit DDR2 AGP 8X Low Profile Ready Video Card
If it is the PCI only model, then for the most part forget about it and make do with what you have because the PCI cards are about twice the price of the above AGP card. That and for the most part the price of the card is more than your computer is worth.
All things considering, with how old that computer is it really isn't worth putting any money into it. You would be better served to hold off until you can afford a new computer, as anything spent on your current one could be considered wasted as when the time comes and you do get a new computer you won't be able to move any of the parts from the old to the new.