Data+Execution+Prevention+DEP

The Data Execution Prevention feature that first shipped with Windows XP SP2 should be enabled by default in Windows 7. When it is, Trojans and other infections will find it much harder to lodge themselves on your PC. You can check, and enable it if necessary, as follows:-
 * Data Execution Prevention DEP **
 * 1) Click **Start** > **Control Panel** > **System** > **Advanced system** **settings**.
 * 2) Click **Advanced**, then under the **Performance** heading, click **Settings.**
 * 3) Click the **Data Execution Prevention** tab.
 * 4) Select **Turn on DEP for** **all programs and services except those I select**.

Click **OK**.