Microsoft has released an early version of Windows Vista Service Pack 1. The add-on - known as SP1 Release Candidate - can be downloaded from several Microsoft websites; for a list see this Microsoft blog post.

Before rushing to download, though, remember that this version is not final, and may still contain errors - we wouldn't recommend installing it on your main, or only, Windows Vista PC, and it's important to back up any important files first. The final version of the service pack is expected early in the new year.