You can "borrow" anybody's XP, then do a Repair install. When it comes time to give the key, use yours. Probably better to borrow the same flavor XP you have. Get your friend to burn you a bootable copy of his XP. Google this for articles to refer to on the techniques.
You will be looking for the Repair option AFTER the eula, F8 screen. DO NOT SELECT THE FIRST INSTANCE OF R.
Install any new drivers you think have to be done. (XP doesn't do a bad job of taking care of drivers.) After that, you will have to re-apply all patches.
When everything seems to be running okay, it's probably a good idea to remove all the, now unused, Device Drivers.
Right-click My Computer - Properties - Advanced - Environment Variables.
Click 'New' below System Variables and type:
devmgr_show_nonpresent_devices (in Variable Name) and 1 (in Variable Value)
Click OK twice. Click Hardware - Device Manager - View - Show Hidden Devices.
Expand all the branches, and look for washed-out icons; right-click and uninstall. MAKE SURE IT'S A DRIVER YOU REALLY DON'T NEED. Be careful of deleting drivers for unconnected devices. You still need those.