Vista's SP1 might not show up on your Windows Updates automatically. This means your PC is currently incompatible and using SP1 might cause problems. Many people aren't aware that Microsoft has released a tool which fixes the incompatibilities and then SP1 will show on your Windows Update, officially supported. http://www.microsoft.com/downloads/...06-D9F1-4700-ACF3-3A58D533597A&displaylang=en (This one is for x64 based systems.) http://www.microsoft.com/downloads/...E2-1AAF-4672-8951-4B7920F982E9&displaylang=en (I assume this one is for 32-bit, but I can't try it since I'm on x64.) Download it, run it. Then, when it finishes, "Check for Updates" on Windows Updates and SP1 should be ready for you if all incompatibilities were fixed. Enjoy.