Mark Angelo - You cannot use mini-PCi modules, they're made for notebooks and barbone/mini computers. Can You post which one You chose? And pros and cons of usb vs. pci-e are as follows:
usb: advantages - portability, size, doesn't take space in computer, disadvantages - poor reliability, often problems with drivers, losing signal, weaker transmit/receive values [due to usb powering], covers lesser area, is taking up a free usb port...
pci-e: advantages - strength of transmit/receive signal and its values, drivers tend to work more reliably, made for 24/7 run, not disconnecting from time to time, better overall reliability [bigger pcb - better semiconductors]disadvantages - takes pci-e slot in computer, non-portable
junkeymonkey - hope there's no hard feelings mate...