I would thoroughly recommend UFO Afterlight to fill in the mean time (you may not complete it by the time XCOM is released) but it will get you in the mood. It has modern visuals with 3d environments and full 360 degree panning.

I think it still has one plus over Xcom with a real time combat and movement (when you move the enemy moves and shoots as well. This is in contrast to Xcom's you move, do your actions, wait, then enemy moves does its actions). Though its still turn based as in weapon "x" takes so long to fire and reload, person "y" will take so long to get item "z" out of backpack etc.

It should be cheap and runs flawlessly (though i am still on XP). The game is designed to be played with not much knowledge and you are expected to figure it out on the go and throughout the course of the game. Kind of sets in to the sotryline that way.

Anyway, if you want a bit of alien bashing, tech building , character progression and exploration - then give this a go. It really is a great "XCOM" style game with good graphics for a small price. (i am still playing it now).