Parallel everytime, it's far easier to install, more and cheaper print servers support it, it's FASTER than usb 1.1 which pretty much all USB printers use, it uses less system resources, it's a decitaded port so it free's up USB ports for other devices, ect.... theirs tons more reasons but just the few I listed are more than enough reason to like parallel over usb.... In anyevent I like RJ45 over both, printers w/ built in print servers are the way to go then you don't have to deal w/ USB or parallel you just plug it into your network and it's over