We recently made a major update to our 'OS Updates' page which lists recommended patches for Windows XP, 2000, Millennium or 98se users. Indeed a very useful resource that covers some important OS updates which not even WindowsUpdates.com features.
Where possible we have linked to download locations from which you can save the actual files in case you need to apply them at a later date, e.g. due to a re-install.
Check OS Updates here.