Assuming you have downloaded the latest EPM 2007 demo VPC, please find below the procedure to convert it to Hyper-V (from Virtual PC); yes I have upgraded my Lenovo T61P from Windows Vista to Windows Server 2008 Enterprise 64-bit to run Hyper-V anywhere!

Within Hyper-V Add Hardware –> Legacy Network Adapter (required to activate Windows later on) ScreenHunter_01 Jun. 24 17.09
Since the host is now 64 bit (Hyper-V requirement in case you missed it) the guest OS needs to be re-activated ScreenHunter_02 Jun. 24 17.13
Activate Windows 2003 again ScreenHunter_03 Jun. 24 17.16
If the network connection worked fine you should see this -> ScreenHunter_04 Jun. 24 17.17
Un-install the Virtual Machine Additions (Add/Remove Programs) and restart the Virtual Machine ScreenHunter_06 Jun. 24 17.20
Using VMConnect, go to Action –> Insert Integration Services Setup Disk ScreenHunter_07 Jun. 24 17.30
Accept all updates and restart the Virtual Machine. You can also un-install the Legacy Network Adapter and use a regular Network Adapter. ScreenHunter_08 Jun. 24 17.41
And voila! image

More info on Hyper-V can be found here: