Officella Windows Vista-tråden

One of the primary benefits of using an x64-based version of Windows Vista is that these versions provide dramatically improved security functionality when compared to their 32-bit counterparts. Most dramatically, the Windows Vista x64 versions include a new secret security feature called Address Space Layout Randmonizer (ASLR) that helps eliminate remote system attacks for the first time on the Windows platform. This feature (which was first disclosed in this very article) ensures that system files load at random (1 in 256) memory offsets at every system boot, compared to previous Windows versions where system files always loaded to the same offset memory location. Because of this change, most (approximately 99 percent) remote attacks will simply fail on x64-based Vista versions.
Working in tandem with the No Execute (NX) technologies in modern x64 microprocessors from both AMD and Intel, Windows Vista x64 versions, like XP x64, also provide support for hardware-backed Data Execution Protection (DEP), which helps to prevent the buffer overflows that are commonly used in electronic attacks. (32-bit Vista versions utilize a less effective, software-based version of DEP.) Another unique x64 feature, Kernel Patch Protection (sometimes called PatchGuard), prevents malicious software from patching the Windows Vista kernel. PatchGuard, Microsoft says, works by preventing kernel-mode drivers from extending or replacing other kernel services and preventing third-party software from patching any part of the kernel.