Official details of the next version of Windows reveal the codename Windows 7, a 2010 release date and the news that Windows will continue to come in both 32- and 64bit editions.

That will cause many Windows users, primarily businesses, to sigh with relief. PC vendors and large software makers, who see more-powerful 64bit 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.

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, 1980s-era PCs with hybrid 8/16bit architectures were limited to a maximum of 64Kb of RAM.

In contrast, a modern PC running a 32bit version of Windows XP can use up to 4GB of RAM. Meanwhile, 64bit 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 32bit to 64bit. And they enable software such as database-driven or multimedia applications that were formerly infeasible on 32bit PCs.

64bit processors for desktop PCs have been available from AMD and Intel since 2004. Microsoft followed, releasing 64bit versions of XP and Windows Server 2003 in the middle of the following year.

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

The last time around, Microsoft was gentle in moving users from 16bit to 32bit, 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 16bit and 32bit. In comparison, Windows 7 will be only the third Windows version, after 64bit XP's arrival in 2005, to sport dual 32/64bit compatibility.

Apple has a similar hybrid strategy. Its upcoming Mac OS X 10.5 ‘Leopard’ is a true 64bit environment that will ostensibly also offer full compatibility with 32bit 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 32bit 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 64bit will be the least happy.

64bit 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.

See also:

Windows Vista review

Windows Vienna due in 2009

Microsoft blocks 'Windows Vienna' debate