Hi juggernaut and welcome to TSF !
You need to take ownership of the old user folders : How to take ownership of a file or folder in Windows XP
On XP Home you'll need to start the computer in safe mode (repeatedly press F8 when the computer starts) and log as "administrator" (leave password blank if you didn't set any). On XP Pro you'll have to disable simple file sharing. You'll find all the instructions in the article from MS.
You need to take ownership of the old user folders : How to take ownership of a file or folder in Windows XP
On XP Home you'll need to start the computer in safe mode (repeatedly press F8 when the computer starts) and log as "administrator" (leave password blank if you didn't set any). On XP Pro you'll have to disable simple file sharing. You'll find all the instructions in the article from MS.