Data Execution Prevention
Data Execution Prevention (DEP) is a new feature for Windows XP Professional that helps prevent code from running in areas of memory where such code should not be running. This helps prevent attackers from placing code in memory to cause default heaps, various stack overflows, and memory pools. This technology does have limitations, though. The hardware that is running on your computer must support this technology, which might be some time in coming depending on how often you change the hardware on your client computers.