Peripheral Ports
Serial Port: "This is the communications port on your computer, also called the COM or RS-232 port. It's called serial because while it has nine pins and many wires, the PC sends data on only one wire and receives data on one other wire. All the data bits have to follow one another on the single wire, in contrast to the parallel port, where eight separate wires transfer each bit of a byte in parallel." -- CNet
Parallel Port: Also known as the Printer Port. It is fairly fast, especially the second version. This port transmits bytes (8 bits) in "parallel". That's why it's faster than the serial port. It's becoming outmoded because the cable is "fat" and it's hard to connect more than one or two peripherals to it.
USB Port: Universal Serial Port. Designed to allow connection of many peripherals to one computer (if you expand the port with a "hub").
High Speed USB 2 is forty times faster (480 Mbits/second) than the old USB 1.1 (which is deceptively called Full Speed and sometimes called Low Speed). Make sure you know how to tell the difference before you buy any "high speed" peripherals, like external drives.
USB 2 may replace FireWire (IEEE 1394) as the high speed serial connection to external devices such as camcorders and disk drives. Most new computers have USB 2 ports. They are backwards compatible with USB 1.1. You can add USB 2 to most computers with an interface card (which comes with the needed software). In the not too distant future Service Pack 1 (SP1) for Windows XP will be released. It will add support for USB 2, but I don't know if existing USB 1.1 ports will be converted to USB 2. You'll probably need to add a USB 2 interface card.
http://www.orangemicro.com/
http://www.usbman.com/
FireWire: This interface was introduced by Apple. It's comparable to USB 2, and is fairly high speed as indicated by the name. It's popular for digital cameras.
Bluetooth: A wireless "port" that allows you to connect PC perpherals without cables. For example, keyboards, mice, digital cameras and cell phones. They have a little antenna instead. It was going to be incorporated in Windows XP late in 2002. Now it won't be. Maybe 2003? There are 3rd party Bluetooth drivers though, for example, in an interface kit from 3com.