I've tested with The Nightmare Before Christmas.
I don't think Windows Update was working when I did my tests, but I was downloading a large file. Could it be the reason?
I have Avast free as my main antivirus, plus Mamutu to block malicious programs behaviour.
Win7 SP1 x64, Intel Core2 Quad Q8200 @2.33GHz, 4GB RAM, several HDDs.
Disc space is not a problem. I did my test with a small trailer of Cars 2 3D. (It has only one audio stream, no subtitles)