I Bought IR:4 pro about a month and a half ago. its awesome ;D . The software is really nice and fully customizable. There are different characteristic settings for the tracking of each individual axis. you can manipulate or create your own profiles to your likeness for the acceleration settings. It doesnt come with much information on programing it, its more of a "oh, if i do this with my head, thats what happens... well let me move this slider and see what happens" and trying out different settings. of course its no problem changing anything in the settings since you have the software minimized in the background while playing FS9. I suggest you get a hat that fits well, and that ventalates well because you'll get "hat head" after the first hour :P . make sure you can put the actual tracking device on top of something ( the monitor) that has a direct line of sight and directly in front of your forehead. Allow room for turning you head left, right, up, down, and the other 3 axes (x,y,z) for vector expansion. speaking from experience get at least something with vector expansion. it will help you when V-cockpits are a bit in the way of looking outside the cockpit, and zooming in/out of gauges. its great when flying with GA aircraft. this is a must have for GA pilots and helo pilots (helps with the landings and hovers))! still great for airliners. althought if you like looking left and right very often (like i do) i suggest to have your FPS at least at 20-25 for great viewing, if its lower than that, its still great but it drastically reduces the realism that TIR adds to FS9. But this device doesnt affect your FPS, so thats a plus

. a flight yoke and pedals would make the experience even more realistic.