Can I put XP x64 and Vista x32 on the same computer in seperate partitians?

Will I have to re-install everything on the partition that I put XP on? I already have vista on my C drive and I am going to put XP on my S drive and I need to know if I can easily maneuver between the two, and if my XP x64 and my Vista x32 can co-exist without tearing the universe in two! Lol thanks!