You can keep private data private on a Windows XP Professional computer by using NTFS permissions. Working with NTFS permissions on a Windows XP Professional computer is easy because the configuration interface appears in the Properties menu of folders and files. Not so with Windows XP Home computers! While you can use the cacls.exe tool to work with NTFS permissions on a Windows XP computer, it's neither easy nor fun. But you can use the GUI to help make your private file private. Try this out:

1. Open the Windows Explorer by right clicking on the Start menu and clicking Explore.
2. In the Windows Explorer find the Documents and Settings folder. Expand that folder and find your account name, then expand that folder.
3. Notice the folders that are under your account name. If you want to make all of these folders private so that other users cannot access the contents of any of these folders, right click on your account name and click the Properties command.
4. Click the Sharing tab. On the Sharing tab place a checkmark in the Make this folder private checkbox. Click Apply.
5. If you do not have a password for your account, a dialog box will appear that asks if you want to create a password. Click Yes and create a password. After you create the password, click OK in the Properties dialog box.

After you make this change, only you will be able to access the files and folders in your user account hierarchy.