If your Windows XP installation forces you to login every time you reboot, you can automate the login process easily so that you won't have to login again. Note that for security reasons, you would usually want to have a password, but for a home computer you may not care. Go to the Start menu, click Run, and type in the following:

control userpasswords2

You will be presented with a window similar to this one: Uncheck the box, and click the OK button. You will be presented with a password dialog for the currently logged in user. Now when you reboot your system, you will automatically be logged in. This can be very useful when you are installing a bunch of software or testing out configurations.