Welcome to LQO
Glad to have you.
We'll get this taken care of for ya
Put in your XP CD and when it boots up choose repair console.
Log on as Administrator or someone with admin rights.
Type ' FIXMBR ' and answer yes. After this you may also have to boot your PC off of something like a Windows 98 boot disk and do fdisk and then make your WinXP partition active (option 2 in fdisk).
With Slackware and Redhat I can do all of this just by doing fdisk /mbr and then going in and making my Windows partition active
Hope this helps dude.