Quoting Snarkasm

Guided partitioning will create a swap for you in the Ubuntu installer.

Jared, I think Vista has some extra stuff that helps the multiple-boot process, so it might change something, but overall, I think this process will help bypass it. You should be fine unless XP's boot sector is a different size.

Vista adds nothing to the process, Windows (and Ubuntu as well) are completely unaware that they are sharing the drive during boot. What the OS sees on the drive after boot is a different story as far as accessing files.

You can swap XP for Vista, and Ubuntu for another distro, provided that the Linux distro gets its bootloader installed to the partition and not the MBR, and Windows gets its MBR backed up and restored before and after Linux partitions the disk.