Shots Fired

Yesterday, I got tired of sitting in front of my computer. Conveniently, I've got my computer set up so that it can easily display to my TV. I got out my Xbox 360 controller, sat down on the couch, and fired up Fallout 3, a game I had previously only played with a keyboard/mouse.

How do you controller people play shooters like this? I felt like I had zero ability to aim, and I ended up taking a lot more damage than usual. Using my sniper rifle was almost impossible, and I had to switch over to my Chinese Assault rifle to actually be somewhat effective.