A PCI adapter is a card which slots into your PC motherboard. It's very simple to install, but some people don't like to do it themselves since it involves opening up your PC. You can get PCI adapters cheaper than USB ones too.
USB1.1 will be pretty badly limited in speed if you have a DSL or cable connection. The easiest way to check the type of USB port is to plug in a USB2.0 device and see if Windows tells you that it can go faster. If it just works normally you have USB2.0. I'm sure there's a more definite way to tell, I just don't know it. Maybe in your device manager or something.