Microsoft released Windows Vista Service Pack 1 in these days, probably in March 18th, 2008. You can update Windows Vista from Windows Updates program.
First click View available updates.
And checked Windows Service Pack 1. And click install.
You’ll be prompted to start Windows Vista Service Pack 1 installation. Click Next.
Check I accept the license terms on. And click ‘Next’.
Click Install to start Installation.
Installation might take sometime depending on your connection. After successful installation, you need to restart your machine.