UK Gamer compared ATI and Nvidia most recent portable chips, ATI Radeon 9600 Mobility and Geforce FX GO 5600.
There is no way to argue with such results.
The Radeon chip is far better than the Geforce.
Should Apple decide to use 9600 in its portable line, especially the 17" model, they'd have to change the motherboard which is made to use a Geforce. This option would be both expensive and complicated. Nevertheless it is to be hoped they'll make this choice.
