First person shooters, normal or inverted mouse?

Been playing Halo 3 on X-box 360, I don't know if it's the knock out classic some would suggest but I quite like it so far, anyway I started playing it and found the controls a bit awkward it wasn't intuitive on the gamepad. A pc is generally far superior for this kind of game with mouse and keypad but I found that inverting the aim on Halo 3 made it far better and a decent gaming experience. However on pc games I played like Half Life and Counterstrike I found an inverted mouse completely unplayable. It just struck me as odd and wondered if anyone else had same experience?