For companies using virtual servers to run critical applications, live migration is highly desirable, since it lets data centers swap running instances of critical virtual servers between physical systems with zero downtime.

VMware has live migration, but Microsoft doesn't, and won't until its next release of Windows Server 2008, due in 2010. When Microsoft officially launched its virtualization products recently, Bob Muglia, senior VP of Microsoft's server and tools business, downplayed the importance of the feature, which in the VMware product lineup is called VMotion. "There is no magic in VMotion. It's just a feature, and we'll have that feature in the next release," Muglia said.

Instead, Muglia and company pushed two themes last week at Microsoft's virtualization launch event: Its products are much cheaper than market-leading VMware, and they fit with the Microsoft software and in-house skills companies already have.

Microsoft chief operating officer Kevin Turner made much of the cost savings of the company's portfolio of virtualization offerings, claiming that a side-by-side cost comparison of virtualizing five host computers would total $21,200 on the Microsoft platform versus $61,400 on the VMware infrastructure. And since most data center staff already are Windows-savvy, using Microsoft tools to manage Microsoft or VMware servers will mean less training, he said. VMware declined comment.

	Muglia: 'No magic' in VMware

Companies such as Heidelberger Druckmaschinen show this competition in action. The German printing press manufacturer started virtualizing with VMware and still uses it on about 10 servers that need the high-availability VMotion live migration feature, says IT director Axel Junghans. But as a Microsoft-SAP shop, it's an early adopter of Microsoft's products, including Hyper-V, and is increasingly using them to consolidate the company's 400 physical servers and reduce and standardize the number of apps on employee desktops.

Talx, a provider of HR and payroll services, is another early adopter of Hyper-V and Virtual Machine Manager where the choice was driven by an existing relationship with Microsoft. "We are a .Net shop for all of our development, and we're moving most of our applications to 64-bit to get better scale," says Bryan Garcia, Talx's VP of technology. Choosing Microsoft virtualization software meant lower training costs, he says.