If you are one of the people that had problems installing Vista SP1 last month, Microsoft says they have fixed the problem and automatic distribution will resume tomorrow. If you've already installed SP1 without any problems then you do not have to do anything.  Word is: "To clear up any concerns for those of you who have already installed the update: There is no problem with the files that make up the Servicing Stack Update (KB937287); the problem some customers encountered was with the installation process for the update. That means if you already have the update installed, you do not need to uninstall it or install the rereleased version of the update."