Apparently, the NTFS drive structure for XP is different than the one for Win-7 or Vista.
Somewhere I heard that if you want to run both OS's, XP has to be the first one installed on the HD.
A much simpler way to run multiple OS's is to have each one on a different Hard Drive.
I'm running Windows 7 and two other OS's right now, with each one and it's associated storage partition on a separate hard drive.
I simply select which drive to boot to by pressing F11 during the first few seconds of boot up, to get my Boot Menu from the Bios.
The different OS's can never conflict with one another because they are on different hard drives. I can either unplug one drive or reformat it and load something else, without ever interfering with any other OS.
For us guys who like to play around with different OS's, it's really the best way to fly!
Think about it......