Can you borrow a XP OEM (NOT RETAIL) version and you can use that to reload your system. Is there a little sticker on the side of the system with the original OS that was loaded along with your reg key?
Download every driver and rename it for the driver it is for...IE Audio, Video, Lan, Chipset.
Put them in a folder on your desktop and then burn them to a cd and mark the cd as Drivers for your HP.
Keep them so you will have them after you do the complete reinstallation. Once you have everything up and running then put the cd in a safe place so you have them for future reference.