In response to my recent post on quickly determining which version of Windows you have, a reader asked the following about his system:
Microsoft Windows XP, Media Center Edition, Version 2002, Service Pack 3.
Is it the 32-bit or 64-bit variety?
Fair enough question: my post covered only Windows Vista and Windows 7, not XP. Know why? Because Microsoft didn't make 64-bit versions of XP--not for consumers, anyway.
Rather, Windows XP 64-Bit Edition was created specifically for Intel's Itanium family of processors, and not many of those found their way into home PCs.
So if you're running XP on your system, I'd say it's 99.9% certain that it's the 32-bit variety.
Ah, but what does it matter? What are the differences between the 32- and 64-bit versions of Windows (often known as "x86" and "x64," respectively), and if you're buying a new PC, which one should you choose?
Short answer: for most home users, 32-bit Windows is fine and dandy. If you're more of a power user, opt for 64-bit (which is increasingly common on new PCs anyway, so you may not even have a choice).
The key consideration is RAM: 32-bit Windows can address only 3.5GB of it, while 64-bit Windows can address 4GB or more. Because so many new PCs come with at least 4GB, that's why you're seeing Windows x64 as the default OS.
I know, I know: this stuff can be confusing. If you want to learn more, I recommend Microsoft's informative article, "Taking the mystery out of 64-bit Windows."