I have xp on one hard drive and i installed vista public beta on another drive in my computer. The install went fine and i was up and running on both os's. I wanted to access my my documents folder off of my windows xp installation and i was prompted by vista that i needed to apply rights to it so i did and i could access my my documents of xp in vista. Now, when i boot to xp, i get errors that my desktop is not accessible, and my my documents is not accessible. Is there a way to give it rights in xp to view these, or can i disable the rights in vista?

Try the Restore feature in Vista. Right click the folder, go to properties and then the Previous Versions tab. Select an earlier date and restore.

...M$ might actually be able to help in this case, ...there's a "Feedback" icon on the Vista desktop that provides all kinds of panes to describe a glitch like that. The "Restore" in Vista should help quicker tho as Laser suggests, ...Start>Programs>Accessories>System Tools same as in XP, ...hope that helps and let us know how you make out ..."the Old Geek"

Wouldn't this be a problem with Vista replacing the NTFS access permissions on the folder? If yes, well, I'm not too sure about Vista, but here's the procedure to reset CP's access permissions:
http://www.daniweb.com/techtalkforums/thread43363.html