Use existing physical ubunu as a Virtual Machine in new installation of Windows 7

I'm using Ubuntu 14.04 on my laptop as normally physical installtion. Because of work, I have to install Windows 7 to works on that OS, but I stil also have to using Ubuntu for another work. So that I want to install Windows 7 as a default physical OS on my laptop, then I will install VirtualBox or VMWare and use existing partition of Ubuntu as a disk in the virtual machine. Of cause this not a dual boot.

Is that possible? And have any instructions in detail please? Thanks for your help.