One Handed Joystick (Please help)

My father recently lost the use of his left hand, and he loves to play games. Up until now he has used the keyboard / mouse for such games as solders of fortune, but he is frustrated that his impairment is limiting his game play (as well as other things in life).

I want to buy him a good joystick, but I'm unsure as to which piece of hardware would do him the most good. He has a 2GHz AMD windows XP based PC, so that at least is current.

Can anybody offer ANY suggestions on a joystick that he can do most of his game play with ONE hand? He is frustrated enough with his situation, so hardware that is easy to use and understand would be best. He just wants to play games, and is not so much interested in the "force feedback" and other gaming frills.

Thank you very much for your help!