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Importing SUS data to WSUS and forcing updates

I've had WSUS import my SUS stuff successfully not once, but twice. The trick is to wait until AFTER you've "synch'd" it; that is, have it contact MS so that it can grab all the patch metadata, then you import the approvals and executables. WSUS is different enough from SUS that the data SUS has on patches isn't enough, so it needs to contact a WSUS server in order to know about the patches... THEN it can accept the SUS data.
And yeah, everyone's been right on the domain bit; it's REALLY helpful to have one, but you can just create a .reg file and use that to add the settings into all your computers.

And on my last note, I'd just like to say the main reason I love WSUS is that, unlike SUS, there's a command you can give ("wuauclt /detectnow") that causes the Automatic Updates client to contact the update server and detect updates right then and there, whereas with the SUS version of the AU client, you had to use clever registry hacks to fool it into thinking at had already started one and needed to resume it. Seems like a trivial thing, but it REALLY helps when building a new system...