Networks Dividing Upstream and Downstream on a LAN

Hi

I have a small network in my home. My main computer is acting as a server computer and two other computers are connected to it (using 2 ethernet cards) . What i want to know is, if there's a way to set up the main computer to act as a router so it can divide the internet up/down stream equally to each client.

Normally this should be done with Internet Connection Sharing but i can't seem to find any option that allows me to set the maximum upstream-downstream usage for the 2 clients on the network.

Thanks for any replies