It's available from Newegg.com and other place.

Armed with that, it's time to read http://forums.cnet.com/5208-7587_102-0.html?forumID=69&threadID=271360&messageID=2699006#2699006

HP may have to reveal where the drivers are and what order to install them.

"but I know the XP installation should be pretty self-explanatory."

Sorry but after installing XP for too many years I can only share it's not self explanatory. The install routing has never been harder. Look at that link above. No one might have guessed that HP would hide drivers on a FTP server.
Bob