You can have Windows running as a virtual machine under VMWare or Parallels, and you can also install Windows as a stand-alone OS on a separate partitition using BootCamp. You would have to install Windows twice -- once under VMWare and once using BootCamp.
You might not be able to activate the second Windows installation -- you might have to buy a second license, or at least be prepared to explain to Microsoft over the phone what you're doing, that both Windows installations are running on the same machine.