if you have a xp disk you can boot to the recovery console.
Boot with the XP installation CD.
When prompted, press R to repair a Windows XP installation.
If repairing a host with multiple operating systems, select the appropriate one (XP) from the menu. If you have only one operating system, enter 1 to select it.
Enter the administrator password if prompted - if no password leave blank.
To fix the MBR, use the following command: fixmbr
windows xp cannot load any operating systems due to the fact allI can get on my screen is BOOT MGR missing