Forget the '7' code name, which was already out there, or the 2010 release date, which was also neither new nor -- based on Microsoft'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.

64-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 percent/15 percent to 78 percent/22 percent.

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.

Apple has a similar hybrid strategy. Its upcoming Mac OS X 10.5, a.k.a. 'Leopard', is a true 64-bit environment that will ostensibly also offer full compatibility with 32-bit applications on, for instance, older PowerPC-based Mac hardware.

Companies, especially those running esoteric or in-house-written applications, will be the happiest to hear that Windows 7 will still support 32-bit software, since it will allow them to avoid expensive rewrites if they decide to upgrade.

It will also be welcomed by Microsoft salespeople, systems integrators and value-added resellers, who will have more options to offer cost-conscious customers.

PC makers and big independent software vendors who may have hoped that Microsoft would push customers harder to 64-bit will be the least happy.

64-bit enables developers to add features and let desktop applications run much faster. Those are much-needed differentiators, now that users are taking serious looks at software-as-a-service applications such as Google Office.

Similarly, because SaaS applications' performance is more dependent upon the Web site's architecture and the user's broadband link, they don't require ultrapowerful PCs. That could remove the need for users to upgrade -- hurting the PC market, or so fear vendors.