Any ideas for a good co op fps?

I was wondering if there's any games where me and a couple of mates could go through in multiplayer co-op mode and complete missions, in much the same way as a single-player game? We're sick of deathmatches and shooting the hell out of eachother.
I heard mention of Joint Operations: Typhoon Rising... Anyone know if we could use this against a computer's AI?
Cheers.

 

Have you tried SWAT 4?

 

Good to hear SWAT 4 has a co-op mode.. I forgot to add that one of my friends only has a 32Mb GFX card
I've heard the Serious Sam games are great, and I'm looking at Delta Force Xtreme as well.
Thanks for the suggestion though, maybe the two of us with decent PCs can work on that one.

 

If your talking about PC games , I cant really help you , apart from online play

But if your talking about Console , a good co-op game is the TS series ( Time splitters ) , its one of my favourite fps's of all time , and in my eyes a complete classic.

Its dirt cheap nowadays as well. Have fun!

 

I personally like Rainbow Six 3: Raven Sheild and expansion Athens Sword

Allows Team Battles, Survival, Co-op Missions, Terrorist Hunts.