call me names if it makes you feel better...
A usb nic has to emulate an ethernet card in software. This uses system resources which a hadware nic does not need. usb uses more cpu cycles. so if your system is "ok" or less than ok, you will benefit from ethernet. i myslef dont like wasted cpu cycles whether i can afford them or not.
hardware is better than software.
usb can only go out about 5 meters, ethernet (cat5) can go 100 meters. you can network with ethernet, usb not so much. gl running usb cords throughout the house to get a network going.
usb can be highly unreliable/stable.
usb networking uses a lot of software/drivers, mostly windows-only or possibly Mac compliant. have fun if you use linux. and if you use 98se or earlier the drivers have lots of problems.
usb drivers can be a hassle to install and get configured correctly.
if you running a LAN its better to use ethernet.
your ping will most likely be 10-20ms faster on ethernet.
a nic card is dedicated to your data. made for it. usb is designed for everything under the sun.
ethernet cards can work in dos, go ahead and try getting usb to work in dos.
only a few. but what do i know, im dumb.