Permissions Bypass

I know someone who has a computer that has a hdd from another computer. The other computer died. The files on the hdd are very valuable to this person, but they can't be accessed. These are windows xp computers by the way. When one of the files are clicked on it asks for a username/password. No matter what is entered it doesn't work. I was wondering if I boot on a Linux live cd (I think I have Ubuntu sitting around somewhere) can I copy the files to another hdd and have access to them. If this works I can copy the file to another hdd, reformat the hdd with original files, then copy them back and have access to them. If so should the other hdd be fat32 so access permissions are not copied and it is still accessible to Linux and XP. Any other method of accomplishing the task of bypassing permissions would be appreciated.

I know it wasn't encrypted. It tried doing something with permissions, but it was so long ago I don't remember what. It would ask for a password, but the password of the old and the new system didn't work. I'll try to take ownership, but I'm not sure that it'll work. I've similar problems with my Vista machine. I've reinstalled many times on it and I find files that I cannot access.