Generally it is not possible to Rename a Guest account in Windows XP but with this simple tip you will be able to Rename the Guest Account.

First Click on Start -> Control Panel -> Performance and Maintainance -> Administrative tools -> Local Security Policy.

In Local Security Settings Window click on Local Policies in the left hand panel.From the right hand panel Double click on Security Options.

Now in the Policy section in the right hand Panel search for 'Accounts:Rename Guest Account' Now right click on this Policy and Select Properties . Now in the 'Rename Guest account Properties Window' Rename the Guest account to whatever you like and Click on Apply -> OK to save the settings.