With the launch of Windows Server 2012 on September 4th we have also released the Microsoft Virtual Machine Converter Solution Accelerator.
The Microsoft Virtual Machine Converter:
Note MVMC also supports conversion of virtual machines from VMware vSphere 4.0 if the host is managed by vCenter 4.1 or vCenter 5.0. You have to connect to vCenter 4.1 or 5.0 through MVMC to convert virtual machines on vSphere 4.0.
This stand-alone tool has a low footprint, is easy to install, and is supported by Microsoft.
You can download the solution accelerator here.