For the new PC gamer: Good FPS games for learning keyboard and mouse

I've done a lot of reading in forums. The number one thing I read is, "just give it a few weeks and it'll be like second nature". Practice makes perfect. But you have to understand, I haven't touch a keyboard and mouse for gaming since Quake 2. Since then I've been a console gamer. I've completely unlearned keyboard and mouse.

The problem I have is that the experience of learning keyboard and mouse is jarring. Really jarring. My favorite shooter on console, Battlefield 3, is incredibly difficult on PC. More players, but not just that. More players who are already well-learned on keyboard and mouse. In other words, the experience has been total sensory overload.

So my question to the PC polynaut community, what PC FPS is a good place to start? Keep in mind that I'm at 0 with keyboard and mouse. Thanks to all those who answer.

P.S, I understand some PC gamers feel incredibly proud of the platform, but I respectfully ask you keep this discussion on topic. Thank you. :)