Broadband service is available from two mediums, cable companies and phone companies. The two use differing implementations of the same technology and can offer high bandwidth at low cost. Most people probably have aDSL, which stands for Asymmetrical Digital Subscribers Line vs. Symmetrical. As mentioned earlier, an asymmetrical connection means that bandwidth or connection speed could be different for your uplink and downlinks. This will vary though cause service providers often offer different levels of service.
Cable service is also asymmetrical.
This all means that life is not going to be very easy for you if you plan to run that server behind your connection. The numbers are against you. We'll explain why in a bit. The real serious connections to the internet are commonly referred to as T1's. Most small businesses will have a T1 connection to the internet.