network is the best route, ethernet can transfer faster than USB and firewire, especially if you move up into the gigbit networking. . . of course this all assumes that the medium of transfer is the limitation, which for your average desktop it is not (pci bus is the common limitor in file transfers).
aside from that a standard network tends to be more reliable.
umm actually firewire is fastest, it supports 400 mb/s transfer speeds. 10/100 is easiest too get workin gon bith pc's thou, if you dont have a network setup just use a crossover cable and set the ips manually and you will be good to go.
Yeah I reccomend network since it will be simpler to setup as well. Anyway, not trying to be rude or anything, just one of the things I find interesting, considering how everything is touted to support such high transfer rates and yet they always come short.
The article you linked to compared the speed of USB 2.0 vs Firewire when using an external HD. In every test, the firewire benchmarks were better. In any event, that test didn't address firewire networking speed.
I found this article that found that a firewire network achieved 44% (approx) better throughput than a 100baseT network. However, they didn't compare it to gigabit.