What can I do to increase network performance?

I have recently upgaded a server to a Dell Poweredge 2950 with dual gigabit nics. All my switches are 10/100 switches and all the pc’s accessing the server have 100 base T nics. The server is getting bogged down trying to fill all the requests. Will it speed up the server if I add a gigabit switch to my network and connect the server to it?