I think this may be off-topic, but earlier on (around Friday, I wonder how this piece of darn news took so long to reach me

), MS validation servers went haywire, so it probably resulted in your PC in being detected as non-legitimate.
This would mean an inability to update all Windows software and even have features turned off.
Can you please try visiting Windows Update site again, re-validate your copy of Vista and see if Windows Update is working properly.
This applies to all XP machines as well.
http://computerworld.com/action/article.do?command=viewArticleBasic&taxonomyName=security&articleId=9032798&taxonomyId=17&intsrc=kc_top