Could 64-bit Windows finally be taking off?

If you build it, it appears they will come, eventually.

Such is the case with 64-bit computing. Advanced Micro Devices launched 64-bit chips for the desktop back in 2003, hoping the fact that it was there and didn't cost extra would convince consumers.

"Our industry, right now, is hungry for another round of innovation," AMD chief Hector Ruiz told the crowd at the San Francisco launch in September 2003. Not that hungry, apparently.

Of course, the hardware wasn't much use without a 64-bit operating system. After several fits and starts, Microsoft finally released a 64-bit version of Windows XP in the fall of 2005.

Still, several factors have held up adoption of 64-bit computing, long after the operating system was available. First of all, there wasn't a lot of need for it. The primary advantage of 64-bit computing is the ability to use more than 4GB of RAM, and until very recently most PC buyers had little need for that much memory. Also, to connect to a computer running 64-bit Windows, printers, scanners, and other peripherals need to have a special 64-bit driver.

But it appears the benefits are starting to outweigh the drawbacks.

In a blog post this week, Microsoft's Chris Flores noted that 20 percent of new Windows Vista PCs in the U.S. that connected to Windows Update in June were running a 64-bit version of the OS, compared with 3 percent of new computers in March.

"Put more simply, usage of 64-bit Windows Vista is growing much more rapidly than 32-bit," he said. "Based on current trends, this growth will accelerate as the retail channel shifts to supplying a rapidly increasing assortment of 64-bit desktops and laptops."

The trend is also evident by looking at the kinds of systems being sold at retailers. In its circular this Sunday most of the desktops and half of the dozen notebook models being advertised by Office Depot had the 64-bit version of Windows pre-installed.

The mix was similar in Circuit City's advertisement, with nearly all of the desktops and many of the notebooks running 64-bit Windows

Gateway, for example, is shifting to an entirely 64-bit Windows lineup on its desktops, starting with the back-to-school shopping season.

It's a dramatic shift even from last quarter, in which only about 5 percent of its total desktop and notebook models had a 64-bit OS installed. For the third quarter, 95 percent of desktop models and 30 percent of notebook systems will have a 64-bit OS.

Among the factors leading to the shift are the fact that 64-bit machines, unlike their 32-bit brethren, can directly address more than 4GB of memory. Also, more 64-bit software is finally coming to market, as evidenced by last week's release of a 64-bit optimized version of Adobe Lightroom.

IDC analyst Richard Shim said he expects even more computers will start shipping preloaded with 64-bit Windows toward the end of this year. "64-bit versions of Windows will begin to find their way into high-end gaming notebooks, which increasingly are being used as high-end notebook workstations as opposed to strictly gaming systems," he said.