One of the problems with running Hyper-V on the notebook PC that I use for work is a lack of hibernation/sleep support. Mark Harrison has posted a partial solution which allows him to hibernate/sleep until he starts running virtual machines:

By setting the Hypervisor/Virtual Machine Support Driver to manual startup (editing the Start key at HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\Services\hvboot to a value of 3), Mark found that Hyper-V can be left installed but not running, then net start hvboot can be used when Hyper-V is required. From this point on, sleep/hibernation will be unavailable (until the computer is restarted).

Unfortunately the main VM I run is the one with the (32-bit only) VPN connection to work that I use to access all of my corporate applications (which I need to access on a daily basis) so this solution doesn’t help me much, but I thought it might be useful to others.