Windows Vista Service Pack 1 (SP1) will reach the end of support on July 12, 2011. From that date onward, Microsoft will no longer provide support or free security updates for Windows Vista Service Pack 1 (SP1). In order to stay secure and continue support you must upgrade to Service Pack 2 (SP2).
More information can be found on the web page here:
Microsoft to End Vista SP1 Support July 12 | PCWorld
More information can be found on the web page here:
Microsoft to End Vista SP1 Support July 12 | PCWorld