As of April 13th, Windows Vista with no Service Packs (also known as RTM) will no longer be supported by Microsoft. The company recemmends users running Windows Vista RTM look at upgrading to Windows 7 or using Windows Update to update their PC to the latest service pack available for Windows Vista today - Service Pack 2.

For more information see this blog post on the Microsoft Support Lifecycle Blog or visit this end of support page on Windows.com.