Protecting Windows customers is an absolute priority for the Internet Explorer engineering team. “We've spent a lot of time talking about some of the more visible safety and privacy features like SmartScreen Filter, but there’re a number of other features that aren't as visible and help prevent vulnerabilities from being exploited, though some are only available on newer platforms like Windows Vista or Windows 7. For e.g., Protected Mode helps ensure exploited code cannot access system or other resources. Address Space Layout Randomization (ASLR) helps prevent attackers from getting memory addresses to use in buffer overflow situations. Data Execution Prevention (DEP) helps to foil attacks by preventing code from running in memory that’s marked non-executable. These defense in depth protections are designed to make it significantly harder for attackers to exploit vulnerabilities. IE8 on Win7 helps protect users with all of these defense in depth features, and there is nothing that you have to do to enable them - they're on by default.