Vista SP1 unavailable from Windows Update?

Microsoft has posted a detailed KB article (KB948343) covering eight possible causes for not being able to install Vista Service Pack 1 from Windows Update.

There are quite a range of causes from language pack issues to incompatible drivers. Definitely worth a read!

The Vista Team Blog has additional details regarding these issues. This blog also happens to have hundreds of user comments attached. Many are complaining about various aspects of Vista and SP1 incompatibility. I suspect it would be worth your time to do a quick search on that page for products you use in your Vista environment. Maybe you'll avoid a few surprises...