The Microsoft Update Blog contains some important information about updates to the Windows Vista SP1 prerequisite distribution plan. Starting tomorrow, we are resuming the automatic update and installation of the Servicing Stack Update.
In mid-April, we will begin distributing SP1 (in the first 5 languages) using the Automatic Update system. We have a lot of Windows users, so not everyone will get it on the same day. In fact, it will go to a small percentage of Windows Vista users each day. The exact timing of when you will receive it depends on when your PC is ready for Windows Vista SP1.
In addition to starting the automatic delivery of the first 5 languages, I wanted to take this opportunity to tell you that also we're on track for the initial release of SP1 in the remaining languages in mid-April.
Source:→ Windows Vista Blog
Windows Vista, SP1, Vista SP1, Update, Windows Update, Prerequisite, Language Packs, Automatic Update, Microsoft Update