I’m a big fan of Sun’s Virtual Box – its cross platform (I run it on Windows 7 X64,OS X and Ubuntu), FREE and works 
Cloning machines is pretty the same as all OS’s, with one slight twist…..
1) Copy the VDI file you want to clone/backup.
2) This file won’t boot because it has the same UUID as the first file you copied, so need to use VBoxManage utility to give it a new random UUID.
3) Open command prompt, and change to your Vbox directory with VBoxMange.exe in it. Probably located at C:\Program Files\Sun\xVM VirtualBox\
4) Run this command in command prompt
VBoxManage internalcommands setvdiuuid “D:\My Virtual Machines\VDI\HardDiskName.vdi”
Obviously you would change the above path to point to your NEW VDI file that you created (not the original).