Microsoft is releasing 12 security updates to patch 57 vulnerabilities in Internet Explorer, Windows, Office, and Exchange Server.
This is a near record for Microsoft for vulnerability fixes. Make sure you install these updates as soon as possible. There are updates for Windows XP SP3 all the way through Windows 8. Shockingly, there are 2 separate updates for Internet Explorer for IE6, IE7, IE8, IE9, and IE10.
One likely cause of the dual Internet Explorer updates is the recent issues with Java. Please make sure that if you have Java installed, you have only the most recent version, currently Java 7 Update 13.
For more information, ComputerWorldUK has a great article on this.
You can access these updates by running Windows Update in your Programs list.