The difference between the J7F2 and J7F4 are the I/O ports...
Looking at the Jetway website, the J7F2 offers a Firewire port and a TV Out in the form or a RCA. I'm looking at getting the fanless 1.2ghz J7F4 myself as I don't need those extra ports and it's slightly cheaper.
As for which MB to buy.... probably best not to ask that here. Just read the FAQ's and check your finances.