It will be plugged in, a la desktop. Thus screen size and power hungry laptops are fine.
Thanks everyone for your inputs. It will be Windows based not Mac for anyone curious.
So far I am looking for something with 4GB (or more) of RAM, 64 Bit Win, external graphics card (preferably Nvidia in my humble choice (but that's another discussion for another day!!!)) and possibly an SSD if its available but I wont worry if not.
As for the game, I would be happy with the battles running smoothly, preferably capable of large battles as you cannot beat a good old tankfest! But I can live with the slow load times.
However with things looking promising on the Eastern Front (eeeee ) and the subsequent 3.0 engine, I am happy to spend a bit more!
Thanks for your input chaps