switches and network backbone

my knowledge of networks is very minimal and would like a solution to the following problem. A private contractor was hired by my company to do 152 points on our LAN. He had been asked to supply a cisco integrated switch so that the fibre cable for the backbone comes from the switch. He instead supplied a cisco 2900 series switch and provided a Dlink transceiver where the fibre was connected. Between the transceiver and the Dlink transceiver is an ethernet link. Is this bound to give us different performance from the one we would have gotten from the integrated switch. The switch is 100mps in speed. I hope i am clear