Full length Aliens - Where to find it.

I attended the premier of Aliens in Sidney AU and it included several scenes not included in most cuts. Notably the scene where the Aliens are attacking and the Marines have set up a series of automated machine guns which almost run out of amunition. I'd like to find a copy which included the above scene plus the later added scenes of the colonists. Does anyone know what it called and where to get it online or on DVD? I'm in California. Thanks, Eek.