Immediately available for download, Hyper-V is free to users of most editions of Windows Server 2008. It is also licensed as a stand-alone product, called Hyper-V Server, for $28 per server.

In comparison, industry leader VMware Inc. charges $2,995 and $495 for ESX Server and ESXi, respectively.

Microsoft is hoping that Hyper-V's lower price and its claim to offer easier management of both physical Windows servers and virtual ones through its System Center and Virtual Machine Manager tools will resonate with customers.

"If you can install and manage a Windows Server, you can install a virtual machine. There is no learning curve," said Bill Laing, corporate vice president of Windows Server and Solutions, in an interview on Wednesday. "Many customers are paying a lot of money for virtualization today. We can deliver better value to a broader set of customers."

Originally scheduled for release by August, Microsoft had already hinted in May that it would put Hyper-V out sooner than that.

InfoWorld reviewer Randall Kennedy wrote earlier this week that Hyper-V, while not as strong technically as VMware's equivalent, would suffice for less-demanding, Windows-centric enterprises.

Hyper-V's Achilles' heel, he said, is its use of off-the-shelf third-party Windows device drivers in creating VMs.

While that gives users more flexibility, Kennedy argued that it also makes Hyper-V-created VMs more likely to fail—and fail catastrophically—than those created by VMware ESX.

Laing said the risk is overstated. Hyper-V will support all of the drivers that work on Windows Server 2008. And server users use far fewer devices—and, hence, drivers—than Windows client PC users, he said.

Beset by delays, Microsoft last summer dropped several planned features in Hyper-V, including live migration, which is the ability to let users shift running VMs between physical servers. Laing said the features are planned to be available in Windows Server 2008 R2, for which there is no announced release date yet.

Laing predicted that virtualization of x86 servers will follow the path of mainframe computers, which started being virtualized in the 1970s and were completely virtualized by the 1990s. The adoption rate will be faster, he said.

© 2007 Computerworld Inc.