Locking Network At 100base T

[Wilson Tuma]

Hi   my network runs on 3com 3c905b-Tx Cards (does dual speed 10/100).  as well as 3coms superstack II dual speed hub. But I have never suceeded in making the network run at 100base T. Is there a way using debian to lock the speed of the network cards at 100base T?   TIA   WFT