Listen to the hype about 64-bit computing, and you could get the idea that the move to 64 bits will make all of your games run twice as fast, replace blocky 3D models with smooth, photorealistic replicas of the human form, and transform the average PC into a wonder-box that can resequence your dog's genome in its spare cycles so he won't pee on the rug anymore. On the other hand, listen to the anti-hype about 64-bit computing, and you could be forgiven for wondering why anyone even bothered?probably just a conspiracy to get us to buy new stuff we don't need. The truth is somewhat different from both of these visions. 64-bit computing won't bring us two times the performance in an amazing overnight transformation of the PC, as the move from 8 bits to 16 seemed to do back in the day. But it's not a pointless exercise in shuffling bits, either. The 64-bit extensions to the venerable x86 instruction set architecture (ISA), including AMD64 and Intel's code-compatible EM64T, actually offer some tangible benefits with few drawbacks. These extensions to the x86 ISA offer a much larger memory address space, bring a cleaner programming model with performance benefits, and retain backward compatibility with existing 32-bit applications.

In order to help you navigate through the hype, we nabbed a pair of 64-bit processors from AMD and Intel and tested them with the latest release candidate of the 64-bit version of Windows XP. Read on for our take on the move to 64 bits, including a look at the performance of the latest CPUs in Windows XP Pro x64 Edition with both 32 and 64-bit applications.