The transition to 64-bit computing has accelerated with the release of Windows 7. Figures published by Microsoft today claim that nearly half of Windows 7 installations—46 percent—are using 64-bit versions of the operating system. This represents a huge upswing in 64-bit adoption; Windows Vista, in comparison, had only 11 percent of its users running the 64-bit version.

The benefits of 64-bit Windows vary; for some users they will be substantial, for others, nonexistent. The 64-bit versions of the operating system have reliable access to larger amounts of physical memory than their 32-bit counterparts. 64-bit software similarly has easy access to more system resources. These factors can provide a substantial performance boost to heavy workloads like databases, but for other workloads—including common desktop tasks such as word processing or Web browsing—there is little advantage to be had.

64-bit Windows software is potentially more secure than 32-bit software. 64-bit Windows can make systems such as ASLR stronger, as known ASLR-defeating techniques depend on the relatively small amount of memory that 32-bit programs have available.

It's these security benefits which prompted Intel's migration to 64-bit Windows 7; the chipmaker, which famously skipped Windows Vista, has expressed no concerns over migration to Redmond's latest platform.

64-bit variants of the x86 processors that power Windows machines have been around since 2003, but the popularity of 64-bit software has lagged behind the processor availability. This started to change with Windows Vista. Driver certification for that OS required submission of 64-bit drivers in addition to the far more common 32-bit drivers, meaning that hardware manufacturers stopped treating the 64-bit version as a second-class citizen. Similarly, software certification requires vendors to test and support their software on 64-bit Windows.

Though it seems likely that 64-bit sales will overtake 32-bit at some point during the course of Windows 7's life, 32-bit software isn't going away anytime soon. A lot of software is still 32-bit, with little to gain from a conversion.

One particular sticking point is Web browsers and their plugins; though the security benefits of 64-bit software are particularly desirable in a Web browser, important plugins like Flash have no 64-bit version. And although Internet Explorer has had a 64-bit version for many years, other Windows browsers have not yet followed suit. This could change soon, as Firefox 4 may include a 64-bit Windows version.

As slow as it is, the 64-bit migration is happening faster than the switch from 16- to 32-bit software. Intel's first 32-bit processor was released in 1985; it wasn't until Windows 95, a decade later, that there was any mainstream 32-bit operating system, and even that was a hybrid between 16- and 32-bit code. Not until Windows XP's release in 2001 did PC users move wholesale to a pure 32-bit platform.