Having problems installing Vista updates? Grab the BITS update

The Vista RTM version of certain BITS DLLs/EXEs have a bug that can sometimes leave the update files/database in a bad state. KB 939159 updates the BITS files to prevent corruption. KB 940520 has a BITS repair tool that helps you clean up your BITS database if it seems to be corrupted.

Best course of action to do if you are experiencing problems: Install 939159, then use 940520 to clean up your database.
Bese course of action if you are not experiencing problems: Install 939159.

Comedy option 3: Join the Vista SP1 beta program and install the beta releases. This is actually my plan, but I like to live dangerously.