Finally… After much testing and releasing new builds, Microsoft has finally made available Windows Vista SP1 final to customers starting today.
Just open Windows Update on your Vista PC and check for new updates. You will see Windows Vista SP1 available there. You can also download the standalone package of Windows Vista SP1 from Microsoft Download Center here.
Windows Vista SP1 Pre-install check-list
- Uninstall any pre-release version of Windows Vista SP1 (the Beta or the RC) that you have installed.
- Update all your system drivers. If you have an incompatible driver then Windows Vista will not show up on Windows Update. Microsoft has a list of known incompatible drivers here.
- SP1 is available in these 5 languages: English, French, Spanish, German, and Japanese. If you have any other language installed, SP1 will not be offered to you. (You might not even know if you have an additional language installed! Check the Language control panel to see what languages you have installed)
Go install Windows Vista SP1. 
Windows Vista Team Blog : Windows Vista released to Windows Update
Nirmal
19 Mar 08 at 11:00 am
Did you install SP1, I’ll wait for the CD version in April. 435MB is too much for my internet connection.
Manas
19 Mar 08 at 1:49 pm
Hmm, I will be downloading SP1 tonight once I return home.
Have holidays coming up on Friday, Saturday and Sunday. Planning to do a fresh install of Vista and then SP1.