It is not the simplest way but it is possible to use raw disks/partitions containing a "real" OS under any virtualization software. At least for VirtualBox, KVM and VMWare and perhaps Xen (not sure, very probably like the others, but I don't use it).
A raw Windows system is probably the least compatible for this kind of use (plus: too many hardware changes usually require re-activation of the Windows license).
Linux distribs and BSD are the most versatile and should not complain much regarding hardware changes if they are used alternatively either as "real" OS or as virtual machines.
Main desktop: Debian GNU/Linux Wheezy 64bit w/custom 3.14 longterm kernel - MATE 1.8.1
(i5 email@example.comGHz - 16GB DDR3 - HD6770 w/radeon driver - SSD+RAID1)