Let's see if the steps will still work to recover the System MBR into Windows 7.
Download and burn to CD
free Partition Wizard bootable CD. Boot PW, allow files to load, select 1 for Screen Res, rightclick System Reserved partition to Delete, OK. Next rightclick Windows 7 partition>Modify>Set to Active, OK.
Now right click Windows 7 partition again, select Resize, drag left border over deleted System Reserved space to include in Windows 7 partiiton, OK. Apply all steps.
After PW reboots to finish resizing, boot into Windows 7 DVD Repair console or Repair CD, click throught to Recov Tools list to run Startup Repair up to 3 separate times with reboots to recover System MBR into Windows 7.
After Windows 7 starts, Add XP using EasyBCD 2.0. Accept boot files, autocompletes, restart.