Over Christmas we had to do a bunch of VMWare to Hyper-V conversions at work. Once you've sufficiently prepared the VM, there are a whole bunch of ways you can do this, ranging from raw converting the vmdk, to mounting the vmdk and a blank vhd and then copying the contents between. We chose it as an opportunity to play with Disk2VHD from SysInternals.
If you're using SCSI disks in your VMWare VM then you will first need to ensure that you add the IDE controller driver, to hopefully avoid a BSOD when you boot under Hyper-V for the first time. Why don't you just set Hyper-V to use SCSI disks? Sadly because Hyper-V cannot boot from SCSI. Once you've added the driver and rebooted to ensure that it's stuck we simply ran Disk2VHD and pumped the VHD off to a network share.
Interestingly Windows 2003 x64 and 2008 were a lot more resistant to the change in “hardware” than older Windows versions, which needed a Windows repair, however I can't fault Disk2VHD for that as it was something I was expecting anyway.
What worried me most was that the first run we did Disk2VHD produced a mangled VHD which I managed to repair and get working by doing the following;
Fortunately all other conversions didn't seem to have this issue, and as much as I would've loved to investigate why this happened, I just didn't have the time.