NO ferraris for GT4 unfortunately, maybe GT5.
The new Logitech pedals + wheel are quite cool, a full 900 degrees of rotation for the wheel, specially designed for GT4. I'm looking at maybe picking one up, as I've heard it really is needed to play the game, not like GT3.
It's a PS2 game, so no computer. I think you can pick one up for $150 USD or so at retail, but they've come out with a new, think PStwo, retailing for $250 USD. Much slimmer, good for travel, but not really necessary.