Always check your BIOS visualisation settings are enabled.
Hyper-V
Windows 10 / Windows 2012 built in. Works well but it can be difficult getting to local disk drives on the host.
Windows Virtual PC
Windows 7 Virtual PC solution.
Existing VHDs are limited to 127.5Gb in size.
Virtual Box
http://www.virtualbox.org
Not compatible with Windows Hyper-V features activated. You'll need to turn them off for access to 64-bit machines.*Issue now resolved since Windows 10 1803*
Existing VHD must be attached via IDE controllers.
Modify VHD sizes using:
vboxmanage.exe modifyhd <pathtoVHDfile> --resize <SizeinMB>
The vboxmanage manual
https://www.virtualbox.org/manual/ch08.html
Tested with 6.0.x to 6.0.4 - It is possible to run the install of a later version installation over a previous version and retain all the VM configuration information.
