it's a real toss up.
You have control over gears with manual, so you can go a gear higher or lower through a corner at a time more convenient than what the computer will do.
Say that the car accelerates too fast in 3rd gear in a turn, a manual will allow you to go up to 4th and drop the rpm. Alternatively, when it is too slow you can go to a lower gear.
The advantage of the auto is that you can devot more contentration to throttle and braking, and timing can be difficult with manuals. You may upshift/downshift at the wrong rpms. Although the computers may not be better, it is probably more consistant.
The old saying goes: If you're really good, use manual. If not as good, use automatic.
(Edited by Talentless at 12:56 pm on July 22, 2001)