We have two Lenovo laptops that have 7 and XP in dual boot. We are now confident that we don't need XP any more, so is it just a matter of deleting the XP partitions?
Reboot and tap the F8 key to see if you have Repair My COmputer on the Advanced Boot options.
If not make sure the Win7 partition is marked Active, then boot installer or Repair CD to run Startup Repair - Run up to 3 Separate Times to correctly do the job of moving the System flag and boot files. It explains in the tutorial why this has been the procedure we've used here since before Beta.