There's a problem with Fedora that changes partition limits when installing it, so it crashs when booting a Windows Operating System.
Take a look at http://lwn.net/Articles/86835/
where it explains how to repair it. I had the some problem as you.
When you get the partition correctly, you'll have to install Windows in a new primary partition, and it installation will overwrite the MBR where you propably have Lilo or Grup, so you'll have to overwrite it another time with Lilo or Grub, setting the boot options for the XP partition and Linux partition.
It's not difficult. Good luck.