Now, OS cd's usually can boot straight to the installation of the OS. So you might have to hit F6 as you boot to select to boot the cdrom, or whatever button your bios asks to boot to that to change the boot order (I like to do floppy drives, cdrom, and then hd's).
Then? you can install over it, or you can do stuff like delete the C: partition and create it again, or see if it has some cd's to set it back to how it was back to the manufacturer's defaults or whatever compaq calls that stuff.
Anywho, yeah, I'm sure that would fix the prob man. But I dunno, if you have some spare cash dude get a better laptop, this one won't be any good for gaming, it'll be decent in surfing the net, creating business documents n' such, but nothing too hardcore.
Later-A-Much, and LONG LIVE THE D!