You can configure Automatic Updates in Windows XP using the System applet within the Control Panel. Click Start, point to Control Panel, and open the System applet. From the System Properties dialog box, click the Automatic Updates tab.
Once there...select the following radio button: Download updates for me, but let me choose when to install them
Click the OK button...and the next time there are updates...they will be downloaded automatically...and you will be notified in the System Tray that new downloads are ready to be installed.