The limiting hardware factor will be the wireless standard used, most cards these days are 11n. So probably not much in it. That said Ive seen some huge differences between cards that in theory at least should be identical.
Just check your pc, and get whatever you have a free slot for
well.. i think i'll get the PCI version as the PCI-E slot is also used for graphics cards and i'll be SLI-ing my GPU's later on and don't want one of the spaces filled up!