Need a new online game!

Hey guys, I am kind of getting bored of CSS and want a new online game to play. Can be any style of game really, but preferably a shooter.

Keep in mind I have quite a slow internet (256k/64k) which is just a broadband connection. 

I was thinking of getting COD5 maybe. I want a game with not to many updates and silly little patches that you have to download. Just one that I can jump on and play whenever I feel like. 

Any suggestions? 

TF2's a great game, very fun class based shooter and it's very cheap (where I live The Orange Box is only 20 euros), has big and mature community, achievements, 9 different classes to play as. And if you could play CSS with your current connection I don't think TF2 will be much of a problem.

The thing I am worried about, is that once I install TF2 would I have to download half the files like I did with CSS?

When I installed CSS from a CD, it made me download the rest of the game from 73% which took 6 hours.