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

In the end, Windows SUS wasn't an option, so I'm using the following in a batch file conjunction with ActiveState ActivePerl (recommended):

perl -nle "print $_ if m/updates detected/i" < c:\Windows\WindowsUpdate.log

This might be crude or dirty, and might break in future, but it currently does what I need.

Thanks for all the ideas.