Is there some reason you're asking a question about wiring in a wireless newsgroup? Not a problem, but I'm curious as to your logic.
I klike IPerf. Versions available for most OS's:
Setup a known good machine running Iperf as a server. Run: iperf -s On the various clients, run: iperf -c ip_address_of_server There are lots of other options to play with. Run the test in both directions with: iperf -r -c ip_address_of_server as creative wiring sometimes causes traffic to work well in one direction, but not the other.
As for watching large files go past, I kinda like to watch the flashing lights on the switch. They're kinda hypnotic and counteract the effects of coffee and running wires all night. If you want detail, setup a sniffer computer, arrange a monitor port or use an ethernet tap (or hub), and use Ethereal or WireShark, with a filter, to monitor the traffic.