Two operating systems on the same partition?

[Silarous]

I just finished rebuilding my PC and Installed Windows Xp 64 edition since I already had it sitting on my desk. Figured I might as well to compliment the new 64bit CPU. Anyways, everything is running great except for a few 3rd party programs I like to used with a few games. I want to install regular XP Pro but have my HD as one single 80gig partition. My question is, Is it possible to have 2 selectable bootable OS's on the same partition? If so, how and if not, Is there a way to downgrade from 64bit of windows to standard 32 without formating the drive? Worst comes to worst, I could reformat and reinstall everything all over again but I would rather avoid that if possible. Thanks for your time.

 

[llama_man]

I'm pretty sure that Partition Magic lets you split partitions. Could be the answer for you.