QuoteThe technology applies only to 64-bit versions of Windows and debuted last year in Windows XP x64 Edition. However, while that Windows version was never broadly adopted, PatchGuard is set to become used more widely, when Vista hits store shelves in January and people are expected to buy PCs with 64-bit processors and 64-bit versions of the operating system. "Kernel patch protection is not a silver bullet. We're not saying no one will ever crack it," Stephen Toulouse, a program manager in Microsoft's Security Technology Unit, wrote on his blog last week. "The point is that the situation as it exists now… attackers don't need to do any work to access the kernel at the highest level. At least with kernel patch protection, we're trying to prevent that."