Download SecurAble, this software is used to check whether your current processor supports NX.

I will be using an vista image to do some settings at the "Data Execution Prevention". Data execution prevention provides protection against buffer overflow attacker, buffer overflow happen when an attacker floods the RAM till its beyond its boundaries. Extra data flow into other adjacent memory can cause computer to stop functioning.

Operating system default setting is that all essential window programs and services will have DEP. Sometimes some software does not require DEP, you can then bullet the "Turn on DEP for all programs and services except those i select". You can then add those trusted software in the box. Sometimes adding trusted software is needed, as some of the software didn't run its full function as DEP is blocking some of its add-on. Adding a trusted software can have both disadvantages and advantages. Advantages is, the software can run its full function without being checked. Disadvantage is, sometimes trusted software may be infected.