Yes, any Windows game could be made to run on an XBox, but this doesn't mean it would be a good idea.

Real time strategy games like WarcraftIII have never been popular on consoles because the controls are wrong. This sort of game needs a mouse and keyboard.

The same thing is true to a lesser degree in games like Diablo II which could be adapted to a console only by removing interface features to get the number of keys down.

To bulk up it's offerings, MS needs console style games.

Jay