Things have changed since my old Atari 2600. Back in the day, I didn't need to use my Engineering degree to play a ##$%$#%! video game. I hear that the Nintendo Wii is pretty easy to use, though. I might look into it when the kids are old enough.
My son has a wii. I am unimpressed. I tried to steer him towards a PS2. Cheaper and better games for now. The wii is still a year off for games.
The mouse-keyboard combination is the best for shooters. Keyboard hand for movement, mouse hand for shooting.