I assume that you are using:
XPH = XP Home
XPP = XP Pro
Since they are both XP, you can use an XP cd and run the fixmbr and fixboot commands, this should solve the problem, but you cannot do it while XP is running, your will need to restart the computer with the cd in the drive.
Bootrec in Vista:
http://www.syschat.com/dual-boot-vis...6.html?garpg=3
Bootrec in XP:
simply type the commands under the recovery console of the XP cd, All commands are flags to BootRec and it is not necessary to type the command BootRex itself. This was changed under Vista.