Can i play 2 xbox 360's on live at the same time on the same connection in one house?

i have 1 xbox 360 and getting another 1 for christmas, my internet speed is is like 2.8 mbs high-speed but im upgrading to high speed turbo real soon, i have a d-link router wbr-2310 pretty basic, my xbox is wired and the new one will probably be wireless, and i was just wondering if ill be able to play them both @ the same time without lag or any problems, and if you have any suggestions about getting a better router if the one specified is not good enough or my connection speed or anything really to help me get a better understanding of what im going to be trying to do thanx.