You were doing it wrong then. Do the same as you do with a single monitor, and add the sidemonitors. NOTHING changes in game, aside from an FPS loss or the ingame HUD. There's a HUD fix for TF2 that you should look for. Puts the HUD elements back to the center screen...
Why was it hard to focus? If you are the same distance from the screen as you previously were, and if you do NOT FOCUS ON THE SIDE MONITORS, then everything is as it was before, but better.
You aren't supposed to look directly at the side monitors.... And they are supposed to be at an angle to the main monitor. All 3 monitors curve in, so that it's like a 1/4th of a circle or something. The monitors aren't supposed to be lined up straight.
Aside from that, your comment makes no sense... Can you please explain?
It's kind of hard to explain, but I feel as if I'm losing my concentration trying to focus on what's going on around my rather than in front. I mean, if you want to look over a corner, instead of adding in another monitor, just move your mouse to that direction and the move it back. I really don't find the extra fov helpful and when I did game using surround site, I didn't notice an improvement in my playing at all.