Presumably it's XP. Is it Home or Pro?
You need to take ownership of the files/folders in question.
If you use XP Home, you need to restart in Safe Mode, log on with an account with Adm privileges, right click the folders, select Properties, Security tab. Click Advanced, Owner tab. In the section "Change Owner to:", highlight the new account, tick the box for "Replace owner on subcontainers and objects", click OK. OK. If necessary, you can enable permissions for the new account under the Security tab, to gain access to the files.