I don't know if this is normal, but I'm currently transfering a 4gig file over my lan to another computer and it's going at 1megaBytes/second.
My main computer, with the large file, is connected to the router with a lan cable (running Vista), and the other computer(running xp) which is connected via a wireless 54g pci card(running at 54g according to the network status).
54g is about 6megaBytes per second and I'm not getting anywhere close to that. My lan connection, according to the network status, is connected at 100megaBits/second. The firewire drive that has the file is running at 400megaBits/second which shouldn't be the bottleneck.