Wrong forum, no problem, I'll move it..
Hmm. From my experience, ME only boots if it's installed in the first primary partition and that it is set active. So I suggest u find out that first. If so, then u also need to make sure that XP made a file I think is called BOOTSECT.DAT for that partition. Not only that, but that file must also contain the bootstrap code for ME and not XP. It should have it if you previous had ME installed and bootable first, then u installed XP afterwards.