I was setting up a WSUS server for the first time the other day and was trying to trouble shoot a issue with a PC that didn’t seam to be registering with the WSUS server.. Found the following command to be useful.

[code]
wuauclt.exe /resetauthorization /detectnow
[/code]

There is a log you can skim through to check for error messages and such located at
c:\windows\windowsupdate.log