file access previous xp sp2 install

I have two partitions on my hard drive, one for the operationg system and the other for data files. I re-formatted and installed Vista on the operating system partition. Unfortunately, I forgot that I had protected certain folders on the data partion through my previous XP SP2 version so the guest accounts could not open these files. Now, under Vista I get a "Windows cannot access the file" error when I try to open the file. Is there a way to recover these files or are they encrypted beyond recovery? Unfortunately, I did not back-up my previous installation of XP as I figured I would do a clean intall if needed as the os was becoming unstable. However, the usernam and password are the same for both XP and Vista Installations.

I have two partitions on my hard drive, one for the operationg system and the other for data files. I re-formatted and installed Vista on the operating system partition. Unfortunately, I forgot that I had protected certain folders on the data partion through my previous XP SP2 version so the guest accounts could not open these files. Now, under Vista I get a "Windows cannot access the file" error when I try to open the file. Is there a way to recover these files or are they encrypted beyond recovery? Unfortunately, I did not back-up my previous installation of XP as I figured I would do a clean intall if needed as the os was becoming unstable. However, the usernam and password are the same for both XP and Vista Installations.