Full duplex is better in Ethernet switches due to the fact that it disables the Carrier Sense portion of Ethernet. This is the portion that listens to the wire prior to transmission. Full allows you to transmit anytime without listening for a quite wire. It also allows you to transmit and recieve at the same time. Full is the way to go, as long as your duplex setting match. Full on one side and half on the other can be worse then half duplex for sure.
Hope this helps,
Don
