Depends on the purpose of the cable. USB is not your typical networking cable, it's primary use is to connect a device to your computer. In some situations it can connect Cable/DSL modems directly to your computer. In this situation it's not technically networking. However, you can buy USB network cards which are much more expensive but do everything a normal internal Network Card does. So like I said above, depends on the use you have in mind for it.
im assuming your trying to choose between connecting a ethernet cable or a USB from your cable modem to your pc i would say USB if it is a short distance as it supports around 200mps ? where a ethernet cable does about 10/100mps depending on your card... no distinct advantage to either other than which one is closer adn less work to get .
Correction: USB 1.1 spec is 12Mbits/sec. Actual throughput will be less than 6Mbits/sec for most devices. USB 2.0 spec is designed to compete with firewire and offers up to 480Mbit/sec. (Actual performance numbers will be less). I'm 99% sure the motorola cable modems eastlink provides are 1.1 spec, but since the device will never see more than 5 Mbit throughput USB 1.1 should suffice. I would still stick to ethernet though, the USB interface on surfboard modems is known to be less reliable than good old ethernet.
5 months on the USB connection (my mac address was already in use on eastlink, i though a mac was suppose to be unique, guess not).... no issues, 600k/sec all day long.