XP is a nice operating system but much of the old hardware items aren't compatible with it. First, you'll need to check the the Compaq website to see if there is a new BIOS driver update for your computer. The BIOS almost surely needs to be flashed/updated IF it's compatible at all. The BIOS update normally is installed from a floppy disk and can be done even though XP isn't fully installed.

Once at the Compaq site, IF you can download the BIOS update, check for other updates such as XP compatible video and audio drivers, ethernet drivers, modem drivers, etc.

There's no guarantee that you can make it work correctly, but if so, you'll need all those drivers.

Hope this helps.