I honestly tried. I spent around 8 hours today trying to play a FPS on the 360 with standard controller and just hate it. Every hour on the hour I kept thinking to myself, "I'll keep an open mind but I feel like I'm using the wrong tool for the job." Oh yes, it's bad when when you consider playing a game a JOB.
There are several keyboard/mouse adapters on the market with the xfps 360 sniper 3.0 being the latest.
Have any of you given these adapters a try? Even if there is a bit of lag I feel like they would improve my game ten fold.