Use drive with both XP and Win7

I just bought a 3 Tbyte USB drive.  I’d prefer for it to have 1 partition, and to be able to back up both XP and Win7 machines to that one partition.  But as far as I can tell, there’s no way to do that-- different drive formatting is required for XP and Win7.  So my next choice is to have two partitions (each less than 2 Tbytes), and back up the XP machines to one and the Win7 machines to the other.  But I haven’t been able to find directions on how to do that-- the sequence of formatting and partitioning.  Can someone point me to directions on how to do that (or, worst case, tell me it can’t be done)?


Maybe this will help  I believe WD has a format tool and you need to select fast format and there is an option about XP if I remember right. Find your drive at WD and it shold be in the downloads.