[sf-lug] linux running windows as a VM

[Alex Kleider]

I've just bought a (second hand/reconditioned) laptop (a ThinkPad T460.)  By default it's running windows;-(
What I'd like to do is install Debian (which I've done many times  on other computers) and then have windows available as a WM should I ever want it. (I've never before had occasion to want it but I've already paid for it so why not have it available just in case?!?)
As I understand it, one can make an "image" (a single file?) of the (windows) OS (and store it on removable media) while running windows as currently installed and then later feed that image to a virtual machine running under Linux (Debian in my case) after Linux is installed (and windows blown away in the process.)
Have I understood things correctly so far and if so, any suggestions as to how to do this?  I've done searches but have been left rather confused by it all.
If anyone can point me in the right direction it would be greatly appreciated.
Sincerely,
Alex Kleider