You could download and burn an XP Live cd (I recently used
http://www.ubcd4win.com/), but it does require an XP CD on disk. That might allow you to look at the contents of the disk and save to the external drive. That assumes that the partition table isn't hosed (which it probably is

).
A Linux live CD (such as
SystemRescueCD) with fdisk and parted may be able to rebuild the partition table, but you would need to know how big each partition was.
Afraid it's not going to be an easy job either way.
Know anyone locally with a XP boot CD to borrow?