For the past few months, I've been tap-dancing around a topic that will continue to gain steam as we move into a year that will be heavy with Microsoft server releases. Although Intel's and HP's Itanium platform will retain its scalability and performance crown for a while, the x64 platform--which combines full 32-bit x86 code compatibility with the headroom of a true 64-bit address space--is coming on strong. I think most people are comfortable with the notion that x64 is the future of 64-bit computing. What you might not realize is that x64 will also quickly replace 32-bit hardware on both the client and the server--and it's happening right now.

The key to this x64 migration is Microsoft support. Last week, Microsoft finalized the x64 versions of Windows Server 2003 Enterprise, Standard, and Datacenter Editions and Windows XP and will publicly release these products in late April. No big deal, you might think: Microsoft has also shipped Itanium-based versions of Windows 2003 and XP, right? Yes, but the supporting cast will take the x64 platform over the top. In addition to Windows products, Microsoft will ship x64-based versions of Microsoft SQL Server 2005, Microsoft Exchange 12, Microsoft Office 12, and other crucial next-generation products. The company will also support native x64 code development in Visual Studio 2005.

But what about the short term? Today, PC makers are pumping out record numbers of x86-based PCs, which are stuck in the 32-bit world with that platform's attendant memory and resource limitations. This arena is where the emergence of x64 computing will see its greatest successes. And those successes will occur in the next 12 to 18 months. That's because microprocessor makers Intel and AMD are already shipping x64-compatible chips to PC makers. And those chips are, in turn, showing up in mainstream PC hardware.

To the casual user, these x64-compatible PCs are ordinary PCs. They run 32-bit versions of XP and are compatible with all the software and hardware that other PCs use. But these new PCs--which typically use Intel's confusingly named Pentium 4 630, 640, 650, or 660 series chips or AMD's more logically named Athlon-64 processor--contain the crucial x64 compatibility that virtually guarantees they'll have a longer shelf life than comparable 32-bit chips.

Why the longer shelf life? First, x64-compatible systems can be wiped out and replaced with a true 64-bit OS. For example, simply switching to XP Professional x64 Edition buys you several capabilities not available in 32-bit XP versions. The 4GB RAM limit--typically with 2GB reserved for the system and 2GB reserved for applications--is dramatically raised to 128GB of physical RAM with a 16TB address space. Even if you run only 32-bit applications on such a system, you'll see the benefits: Each 32-bit application gets a dedicated 4GB address space on x64 PCs.

The benefits don't stop there. In addition to memory-space improvements, XP Pro x64 provides more computing resources across the board, leading to better performance in high-memory and processor-intensive tasks. For example, the paging file has been increased from 16TB in 32-bit XP to 512TB in XP Pro x64. The system cache grows from 1GB to 1TB. And so on.

Performance improves even more when you move to native 64-bit applications. Today, few native x64 applications exist, but Visual Studio 2005, SQL Server 2005, and, in 2006, Office 12 will change that. However, XP Pro x64 will likely see its biggest uptake this year in markets such as engineering and CAD/CAM, digital-content creation, 3-D gaming, and video editing. Developers will likely address these markets with native x64 applications before upgrading mainstream and office productivity applications.

However, like all things technological, the improvements in XP Pro x64 do come with a cost. XP Pro x64 can't use any of the thousands of device drivers that currently exist, so you'll need to ensure that all the devices you attach to your PCs are compatible when you migrate. And XP Pro x64 is incompatible with some, often crucial, 32-bit software. Virus scanners don't work and will need to be updated. Many applications still use 16-bit installers (which won't run) or identify XP Pro x64 as being a different Windows version than XP and won't install or run. You'll need to test applications as well.

I'm not suggesting that you to move to native x64 OSs and applications immediately. But moving to x64 hardware on the server and client now--while still using 32-bit OS and applications for the time being--is a smart move that will likely pay off in the future. The x64 platform is, in many ways, a hedge against obsolescence. And in the fast-moving world of PC software, that's not an opportunity that comes along all that often. If you're interested in Microsoft's x64-based systems, I've written a few previews on the SuperSite for Windows.

Windows XP Professional x64 Edition RC2 Preview
http://www.winsupersite.com/article/reviews/windows-xp-professional-x64-edition-rc2-preview.aspx Windows Server 2003 x64 Editions Preview
http://www.winsupersite.com/article/reviews/windows-server-2003-x64-editions-preview.aspx