Yeah, it'll be the drivers if it worked before. Most drivers turn up in windows update after a while (sound, network, video etc.) but some you may just need to get off the manufacturer's website.
Oops: HP/Compaq are generally great with drivers, so you shouldn't have too many difficulties getting the right ones.
Oh, you did actually mean Compal! Sorry, I hadn't heard of them before.
Unfortunately, their site is apparently 'a joke' according to another person.