The easy way to do this is with the feature of XP called Ownership and permissions. While it's quite incorrect to use the admin account on a daily basis I won't write further about that and dive into file ownership and permissions.

The only prerequisite is the drive is formatted in NTFS. Once that is done all I need to do is select the folders to protect and right click Properties. Then I head to the security tab to remove all other users and add just my account.

Bob