It has been seven years since 64-bit processors started showing on the market and five years since Windows XP x64 hit retail shelves, so both the hardware and software to utilize 64-bit architecture have been available for some time. Still, even with all the necessary components in place, most chose to remain using a 32-bit operating system. In fact, only 11% of computers using Windows Vista were reportedly using the 64-bit version.
The reasoning for this is simple. For some it was due to lack of software support, as up until just a few years ago many popular programs could not work in a 64-bit environment. The other reason is most people upgrade their operating system rather than their whole PC and for those just wanting a quick upgrade path, 32-bit was the only option. So, it has been a long time coming, but Microsoft is reporting as of June 2010, 46% of Windows 7 users world-wide are using the 64-bit version.
The 64-bit architecture has improved security and virtualization over its 32-bit counterpart, but it is the memory capacity most will find beneficial. 32-bit operating systems are only able to utilize up to 4GB of memory while Windows 7 x64 is designed to use up to 192 GB of memory. Of course, there are limiting factors to this, such as price and maximum capacity supported by your hardware, but with the ever increasing demands of software and more people multi-tasking on their PCs, it is important to have as much RAM as possible.
In large part, the increase in the availability of computers with a 64-bit operating system is due to OEMs, and many have moved their entire lineup over to 64-bit support. According to Stephen Baker, 77% of retail PCs in April 2010 had a 64-bit version of Windows 7 installed on them. The increase is also found in the enterprise world, as major companies such as Intel have made the switch over to the 64-bit architecture and it is projected that 77% of business computers will be using Windows 7 x64 by 2014.
In the technology industry, seven years to change a standard is pretty good, and with Microsoft pushing vendors to add better 64-bit support though their Windows Logo program, the 50% threshold should be cleared very soon.