The original classic is now available on Steam for $4.99.  It has been updated to run on new PC running Direct X 9.0c and has support for the Xbox Controller for Windows. It includes all the levels from the original Aliens vs. Predator Gold Edition plus the Millennium Expansion Pack.  In the story on IGN UK, Rebellion CEO Jason Kingley said, "We will in due course fix up the multiplayer – and we'll make sure it's a free download."  So if you want to get pumped up for the new game that's coming, here you go.