Microsoft releases Windows Vista SP2
The update also includes Windows Search 4.0, which is the latest version of Microsoft's desktop search client, plus improved WiFi performance after resuming from sleep mode.
In order to install Windows Vista SP2, you'll need to have Service Pack 1 installed. Microsoft indicates that it might take an hour or more to install the update, and after you're done some hardware (like your sound card) might not work until you install updated drivers.
You can download Windows Vista SP2 for 32-bit or 64-bit processors. Or check out the release notes for more information.