Full Duplex Cable modem suggestions 1

[Snipor]

Since I've connected a router and 5 computers, my network internet connection has been real freaky. Sometimes I would lose my connection, other times, my ping would be so high, I would get disconnected I called the cable company, and the Tech said, the my problme might be that my network cards and Router probably all support full duplex, where my Cable modem doesn't support Full Duplex. I have the surfboard 3100. He saids that that model and the 3com Home connect models don't support Full Duplex. He said I might look into getting a full duplex. He suggested the Surfboard 4100 and the Toshiba's. I went to there websites and couldn't find any documentation stating if these models supported full duplex. Is there a way I can tell, or do you guys have any suggestions for full duplex cable modems?