backup first, just in case.
Shrink that XP
then create the swap partition (2x ram size), the / parition for the OS,
about say 6 Gb, and then /home will be another partition,
you may consider a fat32 as well to share data between OS's
If you have problem partitioning, you may want to use a live cd
like knoppix just to do the partitioning
The Ntfsresize Frequently Asked Questions