Battlefield: Bad Company™ 2

http://store.steampowered.com/app/24960/

This game has awesome visuals, yet still runs really well for a console port. The game features fast paced gameplay set in large open enviornments wtih vehicle and infantry combat. Each class has several guns you may unlock by killing enemies & completing objectives. There is a cool squad based system where you join squads of up to 4 players and may spawn on other members of your squad as well as getting additional points for healing/repairing/resupplying/assisting members of your squad. This encourages co-operation between small groups of players and if you are playing with your friends makes it easy to stick together. The game supposably has built in voice chat but i've never had any success with it so I recommend playing it while using steam group chat or a similar third party program such as Teamspeak or Mumble. The game is heaps of fun when you are on the winning team but can be incredibly frustating when you are with a bad team and the enemy manages to advance to your base.