It is possible by choosing "Use a physical disk" while setting up the VM, however this is
a) bound to be problematic in case the Win7 partition is on the same disk - you'll need a bootloader, and it's normally not possible to choose "Use entire disk" when the disk itself is in use by the system,
b) (more important) Windows may or may not like the hardware changing while booting on different machines (from the windows POV). You may end up with everything from working to 10min+ boot times to an entirely unbootable system! Also, note that the Windows Genuine Advantage may or may not think that the system is pirated after dual-host booting.
Especially for reason b), do a backup before! As for a software, I recommend Acronis True Image, it's cheap.