Most important news about Windows '7': 32-bit to live on

Computerworld - Forget the "7" code name, which was already out there, or the 2010 release date, which was also neither new nor -- based on Microsoft Corp.'s lately abysmal record with hitting major release dates -- exactly set in stone.

The most concrete news to come out of Microsoft Corp.'s well-executed leak of a few sparse details about the next version of Windows is that it will continue to come in both 32- and 64-bit editions.

That will cause many Windows users, primarily businesses, to sigh with relief. PC vendors and large software makers, who see more-powerful 64-bit PCs as key to driving demand for both hardware and software in an increasingly Web-centric world, are likely to have a very different reaction.

Bits of the solution

The number of bits determines how large the chunks of data a component of the PC can process, which determines how much data it can handle and ultimately how fast it can perform. For instance, '80s-era PCs with hybrid 8/16-bit architectures were limited to a maximum of 64KB of RAM.

In contrast, a modern PC running a 32-bit version of Windows XP can utilize up to 4GB of RAM. Meanwhile, 64-bit versions of Windows XP and Vista can support up to 128GB of physical RAM and 16TB of almost-as-fast virtual memory.

Combined, the two techniques can offer steep performance boosts for software ported from 32-bit to 64-bit. And they enable software such as database-driven or multimedia applications that were formerly infeasible on 32-bit PCs.

Sixty-four-bit processors for desktop PCs have been available from Advanced Micro Devices Inc. and Intel Corp. since 2004. Microsoft followed, releasing 64-bit versions of XP and Windows Server 2003 in the middle of the following year.

But while 64-bit server adoption roars along, the process has been much slower on the desktop side. 32-bit software and drivers can be buggy or demonstrate scant performance improvement in 64-bit environments. Those problems can arise even if users are simply moving from 32- to 64-bit editions of the same version of Windows, such as XP.

When under-the-hood changes don't result in better performance, customers will be happy tweaking what they already have.

For instance, during Microsoft's quarterly financial forecast last week, the company lowered its year-ahead forecast for Vista shipments vs. XP, from 85%/15% to 78%/22%.

From 16 to 32, a smooth move

The last time around, Microsoft was gentle in moving users from 16-bit to 32-bit, taking a decade to complete the transition.

Starting with 1990's Windows 3.0 and finishing with 2000's Windows ME, Microsoft released five versions of Windows supporting both 16-bit and 32-bit. In comparison, Windows 7 will be only the third Windows version, after 64-bit XP's arrival in 2005, to sport dual 32/64-bit compatibility.