Re: System restore!
Just do a system restore to a previous date and cancel windows update, simple!
That hasn't always been possible. IIRC the GWX (or a related) update either removed previous restore points or left something on the disk that wasn't touched by restore to make it install itself again as part of the "restore" process.
I can't clearly recall the details (or even if it was XP, Vista or 7) but there was some shenanigans with one of the updates that couldn't be undone with SR.
(I still think SR is perhaps the best thing MS has put into Windows)