When you install SoaSE, the Impulse installer comes with it. Install the program on your second computer and then tell it to update (it should identify that you purchased the expansions and install and update those). Per the instructions in the rule book you can do this in a LAN environment - you do need to have your serial number to setup the Impulse account. And you can only have one Serial Number game connect to the Internet for Internet play.
-Cav
