Microsoft Details IE 8 Security Default Change
Microsoft plans to make a key Internet Explorer default change to thwart attackers trying to hack into its Web browser. The software maker will enable DEP/NX by default in IE 8 when the browser is running on Windows Vista and Windows Server 2008, a major tweak aimed at mitigating browser-based vulnerabilities. DEP/NX (Data Execution Prevention/No Execute) is already available in IE 7, but it's turned off by default because of compatibility issues.