Cisco, Citrix, Novell, Sun and Virtual Iron signed on to the SVVP long before, by the way; so Microsoft's license changes cover all the major hypervisor suppliers.

Unfortunately, they only cover half the Microsoft portion of any virtual machine, Wolf says.

Except for customers who buy Data Center or Enterprise licenses that allow unlimited instances of the OS and applications for a single price, customers have to pay additional license fees for every VM, and those OS instances are limited to the servers on which they're registered.

"A lot of customers would have to double their licensing costs to virtualize their servers, or would have to upgrade to [Windows Server] 2008 Data Center," Wolf says. "If you have a standard edition of a license, you can only assign it to one server. Why not just assign that license to a VM and let the OS move along with the virtual server and the application rather than tying it down to one box?"

Customers with unlimited licenses don't have to worry about the incremental cost of licensing, Wolf says. But smaller and mid-sized companies, which can't afford unlimited licenses and who represent the largest number of customers most likely to be interested in Microsoft virtualization rather than the more-expensive VMware, do have to worry about it.

"We donâ¬"t want people to drive their dynamic IT projects based on licensing decisions," Microsoft's Adam says. "We want them to be able to focus on the real work, the hard work they have to get done. If you have a group of servers and you want to move one instance of Sharepoint or Exchange around the server farm, as long as you have one license for that, you should be free to move it."

Free is good, of course, even when it means "slightly less restricted" rather than "unrestricted and at no additional cost."

It would be nice, Wolf says, if Microsoft would make license changes in large, comprehensive steps, rather than in like this, on incremental, revenue-protecting tip-toes.

Microsoft already has a major price advantage over VMware, so it may not feel much pressure to make things even easier or potentially any cheaper for customers.

But that reluctance will continue to cost customers money they shouldn't have to spend. It will annoy customers it would be better not to annoy. And it will reduce the impact of a licensing shift from grand-slam to a solid double.

Customers will benefit a little. Microsoft probably will, too.