Documents and Settings hidden (WXP-Pro)

[esemce]

I have had an eventful few days, trying to replace the MB on my parents XP Pro box. I did backup, but only to another HD (FAT32), this is now apparently "not formatted". The original boot drive with all the original user data has an issue meaning I cannot boot to XP..I have since re-installed XP to a third drive, and can now see the original boot drive, but not the Documents and Settings (ie all the user data)....is this data lost?? or is it simply hidden because I haven't (can't) booted from the original drive...
If it is hidden, how do I access the data???