If you are not offered Vista SP1 from Windows Update, and you are using an Intel WiFi card (typically with model numbers of 4965AGN/4965AG or 3945ABG/3945BG/3965ABG/3965BG), please grab this full generic "reference" driver package from Intel to fix your wireless issues,
here. 99.99% of the time, these drivers will work on any laptop or desktop with these chipsets.
Originally spotted
here.
In general, if you are running a version of the wireless drivers with a revision date older than 2008, you should install this driver package ASAP. Although it doesn't specifically mention it in the release notes, many little quirks and problems have been resolved, including the Vista SP1 "blocking" issue.
Just to make sure Vista SP1 doesn't get a bad reputation due to this, the "block" was put in place on purpose due to a bug in the wireless driver package, not the OS.
