3Com Nic 905C tx

I am running 7 PC’s peer to peer using 3Com
100 mbit 905C TX cards. I also have a 3Com
10/100 mbit Hub. The network is running slow and I am detecting collisions at the hub.
I have configured the Nics to run full duplex at 100 mbit for the media,still getting collisions. How do I eliminate this. The systems are 3 Win 98 SE, 1 NT 4.0 Workstation, 1 Millennium, 1 98 SE Laptop and 1 Win 2000. Any help would be appreciated.