I should've remembered and used this on the Lifebook's Vista install to begin with!
Legacy Update is a project that fixes the Windows Update service in older Windows versions, and allows it to search for and download updates again — and, in the case of I believe Vista and above, even right through the original Control Panel applet.
There are no updates available for your computer.
That is very cool.
Initially, I just manually grabbed and installed updates that I found mentioned in various places online as important for security, stability, etc., but that's very tedious (Microsoft's Update Catalog is not terribly user-friendly, and maybe it's not meant to be?) and I didn't even get all the updates that MS itself actually considers critical, as after installing Legacy Update, Windows Update found several more I missed, plus a host of updates for the copy of MS Office 2003 I installed for fun and nostalgia.
So yeah, can confirm that this project makes short work of updating at least Vista, I guess! I have yet to try it on another OS, but I might do so on the ol' first gen Core i3 Dell laptop running Windows 7 that I still have sitting around, from before I got the ThinkPad T430. That's probably lacking an update or two, too.