You don't need a special bus to use firewire, you can put a firewire card into a pci socket on your motherboard.
You cannot get nic's that use firewire as far as i'm aware - the hard drives you speak of are external models that use firewire connectivity because of its high bandwidth. If you want a super fast network - you could use a gigabit ethernet nic, but you'd need a gigabit switch to feed it.