Nice to see you fixed it. I'll post this anyway in case anyone else runs into the same problem. There should be no need for a live cd or anything to fix that sort of problem.
Basically you need access rights to both the files and folders. The easiest way is to do that use the "Advanced" portion of the security tab to propagate the necessary entries to every file.
Go to "My Computer"
right click on the xp drive you want to take ownership of
go to the "security" tab
click "advanced"
Make sure you are in the "permissions tab"
Click "Edit"
If you just want the files to be accessible to yourself, see if your user account is already listed. If it is, then click "Edit" and give yourself "Full control" or "Read and Execute" permisisons as necessary. Otherwise click "Add" to create an entry for your account, give yourself "Full control" or "Read and Execute" permissions.
If you want the files to be accessible to anyone, click "Add", and create a "Read and Execute" entry for "Everyone"
Make sure the checkbox for "Replace all existing inheritable permissions on all descendants" is checked.
Click "Apply", wait for the permissions to be applied to everything.
Profit!