Looking for a New Multiplayer FPS

Greetings -

Looking for a PC game that is similar to Battlefield 2142 in the customization aspect, with things like unlocks that allow varying accessories and different weapon types.

There are some system limitations, but feel free to suggest anything.

Really looking for something team-based, and includes vehicles.

Thanks!

Quake wars sounds like exaclty what you are looking for, its cheap as well