Hi I have a sidewinder FF 2 aswell, and mine works fine in arma just I set it up in windows (Both vista and XP) control panel and assiged functions to the axis etc in arma options. Â Note its the only controler i have installed. Â If you want to have 2 controlers enabled you need to setup a virtual controler it was mensioned in these forums, just do a serach covering the last year and you should find it.
Disabling the other controllers should work.