I suspect part of your problem is the XP version you are trying to run concurrently with the other programs. If you look at the EasyBCD website, you will find instructions for including XP in the boot manager process. Once you have that resolved between XP and Vista and the boot process works smoothly, then try loading Win 7 onto a separate partition. I don't have XP on this computer, but I do have Vista 64, Win7 64, and Win7 32 all cleanly loaded onto separate partitions and I can easily switch between them upon restart through the boot manager. I also have a separate partition for data, which helps from creating three versions of the same stuff (music, pictures, videos, etc.) for each operating system.
Good luck, let us know how it goes.