One of the great things about Windows 7 Professional and Ultimate is XP Mode. Windows 7 will run a virtual Windows XP so that the OS can maintain full compatibility for old applications that don't work in Vista or 7.
In order for XP Mode to run, however, the CPU must have virtualization support and the feature must also be enabled in the BIOS.
While one would think that being able support virtualization is a great feature and selling point, Sony seems to be intentionally disabling it on its Vaio computers due to security concerns. Whatever those concerns may be, other manufacturers don't appear to be worried enough to cripple their own systems.
Xavier Lauwaert, Senior Manager Product Marketing at Sony, explained in a comment on the Windows blog, "Contrary to perceived opinion, we have received very little if any requests to enable VT technology up until very recently.
"In addition, our engineers and QA people were very concerned that enabling VT would expose our systems to malicious code that could go very deep in the Operating System structure of the PC and completely disable the latter."
Lauwaert added that with the advent of XP virtualization, Sony will be reevaluating its stance on the technology and will be enabling the feature on select models.