triock: Press the Backslash key (\) to run the game in a bordered window, instead of full screen.
DeMignon: That doesn't switch to windowed mode, but only offers an alternative full screen mode (see screenshots)
Orionos: ... Anyone know if it's possible?
DeMignon: As far as I know, it isn't possible to run the game in real windowed mode out of the box. If you really need it that way, you could install a virtual environment like (VMware or VirtualBox or Window's Hyper-V which is included in the Professional Edition) and run that in windowed mode.
Alternatively you could use the DirectX wrapper
DxWnd. It intercepts the DirectX fullscreen graphics output and redirects it to a window.
DxWnd worked. I figured the game wasn't using DirectX yet. Although my whole system slows down to a crawl until I close Firefox, strangely enough.
Thanks.