Microsoft revealed that it has carried out negotiations with all the major Original Equipment Manufacturers in the United States on the Redmond campus in order to convince them to support the Randomization feature in Windows Vista. Following the discussion, Dell, HP, Gateway and other computer manufacturers have given a thumbs up to Windows Vista Address Space Layout Randomization.

In doing so, the OEMs have agreed to enable P/NX in BIOSs by default. Modifications at the BIOS level are necessary because Vista ASLR can function only in the context of an enabled Data Execution Prevention/No eXecute. ASLR is a security feature in Windows Vista that enables the operating system to randomly alter key data areas locations. In doing so, the operating system gains increased immunity against malicious code attacks by stopping buffer overflow techniques through the memory-space randomization technique.

In Windows Vista this is the way to verify if your PC has DEP enabled:

1) Open the Control Panel
2) Select System & Maintenance
3) Click System
4) Click Advanced system Settings
5) Click the Advanced tab
6) Click Performance Settings
7) Click the Data Execution Prevention tab

If you have followed the steps presented above you will be able to see the dialog box comprised in the adjacent image. The dialog box will be revealed if your machine supports DEP/NX, and will additionally give you control over the interaction between DEP and the programs and services on your system.