Xbox game controller to use with pc

If I get the Microsoft Xbox 360 Wireless Controller For Windows, it comes with a receiver for the pc that will then work with any modern wireless x-box conroller, my question is - if hubby and son want to play 2 player game like lego starwars, will they need a receiver each or will the one receiver receive both controllers?
Not ready to upgrade from ps2 to a ps3 or xbox yet so this seemed a good way of getting the new games that they are no longer releasing for ps2.