Legacy application support means moving from one OS to a new one, but if a few critical apps don't work on the new OS, that's a problem. A virtual legacy machine allows you to use those old apps and you don’t have to hold off the whole migration. And also, you can deposit your image of a PC anywhere you like. Longhorn is going to be the biggest migration since Windows 95 and it's going to be painful, so it's right to move now to deal with that. Market pressure is there. If you look at some of the Longhorn technical security features, they certainly give the impression that some support for virtualisation is built in.
How about Intel's role in this?
Both Microsoft and Intel have a vested interest in easing their user's migration path. Intel has announced hardware support to help isolate virtual machines and keep them secure. They will also have to allow privilege level support that will help you enforce installation and closure around a virtual machine.
What's the big pay-off for enterprise customers?
The big attraction is that deployment best practice is something that few organisations rarely achieve. Ideally you would lock users down, so you can intervene quickly. The measure of your exposure to a risk is the time from announcement to patch, and the more standardised your desktop the quicker you can intervene. We may actually see legal cases where companies who are unable to submit reports or deliver service because of infection and haven't followed best practice will get sued. And if people face litigation they will be under much more pressure to achieve deployment best practice.
What does this mean for the future of software licensing?
I think in the long term it drives a horse and cart through the current licensing paradigm. When Microsoft announced changes in product-use rights in October 2003, close to the date they launched virtual PC, they made it possible to install two versions of Windows on one machine. It's the first erosion of the licensing paradigm, and it takes out dual OS cost.
