"or do i just live with XP missing the Vista partion"
That may not be such a bad thing. Have a read of this page No restore points are available when you use Windows Vista or Windows Server 2008 in a dual-boot configuration together with an earlier Windows operating system
It explains how every time you boot XP in a Vista and XP dual booting setup, XP ruins the contents of the System Volume Information on Vista's partition. It deletes Vista's restore points, and also the Complete System Backups (a feature available in Ultimate and Business but not the Home editions). The workaround recommended by Microsoft is to hide the Vista partition from XP, using a registry edit in XP. You can still share documents between the two OSs by saving them into any partition except Vista's.
Alternatively, if you want to be able to read and write files in Vista's partition while in XP, you might as well turn off the system restore feature in Vista (so it doesn't save any restore points) which will liberate some disk space.
If you are saving images regularly with Ghost, system restore is not so necessary.
Also using Ghost or Acronis TrueImage or Seagate DiskWizard to save disk images is much better than using Ultimate's 'complete system backup' feature.