Hyper-V will hold a significant cost advantage over products from VMware, which dominates the server virtualization market. But in tools for the management of performance, provisioning and security of virtual machines, VMware still holds a large lead, most analysts agree. Microsoft is quickly adapting its own physical-server management software to handle the virtual world, but has not yet caught up to the capabilities of the tools VMware already has available, they say.

Still, Hyper-V is a "huge advance" over Microsoft's previous entries in the virtualization market, Woolsey says. Direct performance comparisons between Hyper-V and Virtual Server show that Hyper-V "smokes Virtual Server in virtually every configuration," Woolsey says. Tests from Intel and Microsoft partner QLogic show the same result, largely because of Hyper-V's more efficient approach to input/output and virtual network-interfaces, Woolsey says.

Hyper-V also scales much more efficiently than Virtual Server, with each new VM adding very little overhead to slow things up, Woolsey says.

"We have 26 customers across a lot of verticals and sizes who are running Hyper-V on a total of more than 100 servers, running from four to 10 guest sessions each," Morimoto says. "We had one customer we quoted a project at about $275,000 for hardware, software and services, for 40 servers and all the software required. The price was just too high, and the deal fell off the table. Later on we were able to include them as an early adopter. We were able to do the same thing with a third of the equipment and virtual servers, plus all the services, and we could put it in for about $140,000. It was less for the customer to spend and it was great for us because it increased the services part of the bill by 30 or 40 percent, and the margin on services is a lot higher than on hardware; you can't make any money just selling hardware."

Saving money is a good justification for virtualization, but not as good as agility, Steffen says. "We can reconfigure servers, move things around, provision a new server in 15 minutes for failover, or DR or a new task. That kind of flexibility helps make us a lot more nimble than our competition."

The release of Hyper-V, especially in a high-performing, stable iteration, will put a lot of pressure on VMware, Steffen and Morimoto agree.

"VMware can focus on adding value, focus on the management part, but honestly, Microsoft has a pretty good story on the management front. It owns the management stack from SMS and the rest of the stuff it's done for physical servers," Morimoto says. " We've made a lot of money selling VMware, but Microsoft has addressed about 80 percent of the high availability stuff VMware has, including failover clustering. There's no question that ESX is a great product, but you can mix it with Hyper-V and it works the same."