Just a heads-up for those of you who are MSDN subscribers. Vista's Service Pack 1 is available for download!
I downloaded the DVD ISO file. That gives me all the x86 and x64 versions in English, French, German, Japanese, and Spanish. They also have a smaller EXE download available as well.
I just finished installing it. Be forewarned that this install will take about an hour to complete with several restarts of your system. The good thing is that you can check an option to let Vista automatically restart during the process so you can leave the install unattended. There are no options to set or choices to make during the installation process. You just let it run. I'd suggest letting the install run during your lunch hour or at the end of the day.
I'll have to let you know if I notice any performance improvements later. I've only had SP1 installed for a few minutes and I can't really tell how things have improved (or become worse). I did take a full disk image backup before installing this so that I can revert if necessary.