Are you looking for a WWII-FPS? Then Battlefield 1942 is your obvious choice.
Gunfights between soldiers on the ground. Airplanes bombing the ground with devestating power. Tanks crushing the bones of enemy soldiers. Gigantic battleships along the coastlines. Battlefield 1942 offers great graphics, wide battleareas and a lot of vehicles to control. The fact that it origins from Sweden doesn't make it any worse.
Multiplayer-battles with up to 63 other players over the Internet or a Local Network, or battles against computer-controlled bots. And it's all extremely fun. The only setback is that to enjoy all the glory of this game you need a powerful computer and a highspeed Internetconnection otherwise the games flow will most definetly be compromised.