Windows PVM all I need to back up for a reinstall

I have windows 7 installed as a expanding drive install. In order to back up my windows install, all I have to do is make a backup of the windows pvm file ? the file is about 20 gigs. the size of my windows install. im hoping I can make a backup of the windows pvm file and if something happens just drop the windows pvm in my parallels folder and be good to go.

I dont want to trigger another windows license install. is there anything else i should back up?