Best way of detecting if Windows has Windows Updates ready to download/install?

Question

I\'m specifically interested in Windows 2000/XP, but Vista/7 would be interesting too (if different).

I was thinking along the lines of task scheduling a batch file

Answer 1

The "easiest" way to tell is to setup Windows Updates to occur nightly and download the updates if available which then puts the update shield icon in the system tray. Just glance at the tray to see if the icon is present.

You could also setup Windows to check nightly for the updates, then download and install them at a specified time.