Steam has opened pre-orders on the sequel to the widely popular survival horror FPS, BioShock. Slated for release on February 9, purchasing BioShock 2 now will score you a 10% discount that brings the price from $49.99 to $44.99, as well as a free copy of the original BioShock.

Steam is also taking advanced orders on Aliens vs. Predator, which costs $49.99 and is scheduled for a February 16 launch. Unfortunately, there's no discount involved, but you will receive a $20 copy of Universe at War: Earth Assault, as well as three unique in-game skins: SGT. Kaneoko, Number Six, and Alien Head Predator.

If you already own BioShock or Universe at War: Earth Assault, you can give the extra copy to a friend. It's also worth noting that both of these titles made our Most Anticipated PC Games of 2010 list.