Scotty

The speed of USB 1.0 should be fast enough for your connection, although it isn't speedy, the connection to the Internet is slower then that.
An ethernet version is perferable (in my mind) but not necessary in this case.
USB is fast and easy.
My DSL "modem" is a standalone unit that just connects to my network and then to my firewall, then to all of my machines. I am at something like 1490 meters and get 768/128 and that is as fast as I can go.
I have looked into "dry copper" lines for work to connect between my ISP and my office, then I can get two direct phone lines and equipment and have 2.4mb which would help out. The phone company has not been too supportive, as it would be so much cheaper for me to do...

-Scott

Kinross

Depends on what your download speed is. Most DSL modems are USB 1.1 which is maxed at 12 Mbps shared across all devices on the USB bus ie mouse, printer, scanner, camera. Sustained data rate for USB is typically 1 Mbps.

So if your download speed is greater than 1000 kbps the bottle neck will be in your USB connection.

Ethernet to a DSL modem is 10 Mbps sustained so the bottle neck will always be outside your home.

If you have the slot I'd go with Ethernet.