Vista - Can't access 2nd Harddrive files after switching back 2 XP after V

I had installed vista onto my 2 hard drive computer. And after installing
Vista, I had to change the permissions for most of my files on my 2nd hard
drive so I could actually access them with Vista.

After noticing how slow vista is, I switched back to XP. Now I cannot access
the files on my 2nd hard drive. Everytime I click one of the folders like
lets say D:\Documents and settings\User\Desktop it says "Not accessible,
Access Denied"

How do I switch the permissions back? Thank You