A while ago I blogged about some fun at being an early adopter, the issue that caused it was that Vista wouldn't update. Funny enough the new stuff didn't help a bit, not even a little bit. What was happening was I was getting that error while not connected to the work network due to my machine being set to get it from the company WSUS server. While on the network I got a different error (8007000b if I remember right)
For love or money I couldn't fix it, until I stumbled on the fact WSUS 3.0 was released. Upgrading the company WSUS server to that fixed the problem. Seems we were using a RTM of 2.0 and Vista support was only added in 2.0 SP 1 :(
Regardless 3.0 is really worth the upgrade. Only problem is now I am getting new patches almost every day until I catch up to all of them.
Anyway grab all the yumy WSUS freshness at http://technet.microsoft.com/en-us/wsus/default.aspx