Realtek NIC 10mbps conection to 3COM Hub

I have three Windows ME PC’s that have Realtek 10/100 NIC and connects to a 3COM 10/100 OfficeConnect 8port Hub. My problem is that I only get connection at 10mbps in half duplex. I try the autosense feature and manually set the speed in the NIC’sat 100mbps half duplex with no success. Before I install the Realtek NIC, I use a CNet 10/100 NIC and have the same problem. So I suppose that the problem relies on the hub or at Win ME. Do I need to replace the NIC to a 3COM NIC? Replace the Hub? What can I do? Thanks