One of the best-kept secrets about Windows 7, its support for a Virtual Windows XP mode, has become a potential headache for a lot of computer users who want to keep running fussy legacy apps under Windows 7. To maintain high system performance, Virtual Windows XP Mode requires the processor to support hardware virtualization (and the system BIOS must enable the feature).

As ZDNet's Ed Bott reports, trying to figure out which Intel processors have hardware virtualization (known in IntelLand as VT support) requires a lot of time with the Intel Hardware Spec Finder. Ed spent the time, so you don't have to wonder about Intel desktop or mobile CPUs (but check the update on page 1 for news about some CPUs that are getting updated to add VT support).

What about AMD CPUs? That's a bit easier to figure out, thanks to a statement from an AMD spokesperson quoted by Cnet:

All CPUs AMD is currently shipping, except Sempron, include AMD-V and therefore support XP mode.With the exceptions of Sempron-branded processors and Turion K8 Rev E processors, all notebook processors shipped by AMD include AMD-V and therefore support Windows 7 XP mode. With the exceptions of Sempron-branded processors and pre-Rev F Athlon branded processors, all of the desktop processors shipped by AMD include AMD-V and therefore support Windows 7 in XP mode. Also, all AMD Opteron processors shipped by AMD from Rev F forward include AMD-V.

Want an even easier way to get the virtualization scoop on your systems? PCWorld recommends the SecureAble test page at the Gibson Research Corporation website. Run SecurAble to determine if your processor supports hardware virtualization, hardware data execution protection (DEP) and to learn if it's a 32-bit or 64-bit CPU. Give SecurAble a try and let us know if you found any surprises about your system.