I'm not sure I understand all of your question or how you got in this state.
So you installed XP onto your hard drive using Boot Camp which partitioned your disk into two separate partitions.
1. Why did you think that your did not have any files left on the Mac partion?
2. What prompted the Format of the Mac Partition and what did you use to format it?
3. With the use of a decent file recovery program, you "may" be able to pull stuff the Mac partition, even after you formatted it, but that would suppose that you could actually boot from that partition. Can you?
4. Did you think that you had lost all your data because you could not see the Mac partition when running Windows. (Without the use of third party software, windows cannot read from, or write to an HFS+(Journaled) disk which is what your Mac partition was formatted as.

P