In Virtual Server 2005, the ideal method for migrating a virtual machine between hosts was to simply copy the associated files over to the new server. This still works in Hyper-V, but doing so will result in quite a few of your custom settings not being copied over to the new host. Doing this will also result in the settings of the virtual network card within the VM being moved to be reset, causing you to lose your IP address settings.
The preferred method for migrating a virtual machine in Hyper-V is to use the Import/Export features of Hyper-V. In order to export a virtual machine, you can simply right-click that VM within Hyper-V Manager and choose the Export option. During the process you can choose to only export the VM settings, and not the VHD files itself if you so choose. On the new virtual host you want to import to, you can do the same process in reverse by choosing the Import option from the Action menu in Hyper-V Manager.
Performing a migration between hosts in this manner will assure all settings are copied along with the VHD file, and ensure that network adapter settings are not lost as well.