also 384k, 512k, 1mbit, 2mbit, 4mbit. 8mbit, 20mbit, 24mbit, 50mbit, 100mbit. No-one has gigabit apart from patton's office.
I doubt it, if you use a router the speed your computer says will not be the actual speed of your net connection, it's the speed between your computer and the router. For example, my computer says connected at 1gbps, but it is only 1gbps in my room. The line from my room to the firewall (router) is 100mbps, and the actual net connection is 1.5mbps.
the same applies to cable modems and any other form of connection that uses the ethernet (network) port on your PC.