Microsoft is ending support for Windows Vista SP1. Windows Vista SP1 will be past very soon after July 12, 2011.
Ending of support means that Microsoft will no longer provide updates for Vista SP1. So it is advised to upgrade Windows Vista SP1 to SP2 as soon as possible which is available at no cost.
After July 12, Microsoft will focus exclusively on Service Pack 2 only and continue support Vista SP2 until Windows Vista life cycle, if SP2 is the last major upgrade for Windows Vista.
Service Pack 2, the latest service pack for both Windows Server 2008 and Windows Vista, supports new types of hardware and emerging hardware standards, includes all of the updates that have been delivered since SP1, and simplifies deployment, for consumers, developers, and IT professionals.