One of my recent projects has been a UC PoC built around Server 2008 R2, Exchange 2010, SharePoint and Office Communications Server 2007 R2. Trying to be as green as possible all but the first DC in these environments has been virtualised using Hyper-V Server R2 on HP Proliant ML110 G5’s.
Due to a little bit of a delay with some of the servers I initially built the lions share of VMs on a single box and have subsequently transported the VHDs to the additional hardware as it arrived. Most of the guests were Server 2008 R2 servers and overall the experience has proven fairly painless, with one exception.
Moving VHD’s between machines running the same virtualisation technology is very straightforward, all of the virtual hardware the OS sees is the same, the one gotcha relates to the network cards, with the NIC on the new machine installing afresh - goodbye ‘Local Area Connection’, hello ‘Local Area Connection 2′. Even then, this isn’t the end of the world as IP addresses can easily be reassigned (and Server 2008 R2 will offer to remove conflicting IPs from the old ‘ghost’ NIC). The one cause for difficulty becomes any configuration where the name of said NIC is important as even when not connected the name is reserved and finding the offending adapter can be a bit of a pain.
The MMC as default doesn’t show old devices, after a bit of trial and error and a lot of hunting around I’ve found that the following from an elevated command prompt will do the trick:
set devmgr_show_nonpresent_devices=1
start devmgmt.msc
Et voila, device manager loads showing the old offending NIC which can then be deleted, freeing up the previously reserved name 
Screenshots – before and after with ’show hidden devices’ enabled:
