Install the Cumulative Security Update MS10-018 for Internet Explorer

http://www.microsoft.com/technet/security/bulletin/ms10-018.mspx

This security update resolves nine privately reported vulnerabilities and one publicly disclosed vulnerability in Internet Explorer. The more severe vulnerabilities could allow remote code execution if a user views a specially crafted Web page using IE6 and IE7, and does not affect users of IE8.  We highly recommend customers to promptly install this update to help protect against these vulnerabilities, and upgrade to IE8 to benefit from significant security enhancements as well as reliability and performance improvements

Upgrade to IE8 by leveraging the Internet Explorer 8 Deployment Guide

http://technet.microsoft.com/en-us/library/cc985339.aspx

The process of deploying Internet Explorer 8 to your organization's computers is organized using this deployment guide.