T1 Connectivity

My LAN consists of about 50 workstations with 4 NT 4.0 servers. Currently we have 15 users connected to the internet using standard modem lines. We are finally going to have a T1 line installed to our office to eliminate all of these dial up accounts and to allow more users internet access.My question is,can I use one of my existing servers to act as a gateway and/or proxy server?What would be the best way to accomplish this?