I'd be interested to hear of actual MB/sec throughput from timing of your file transfers. I have a Linksys 54G Speedbooster router with Speedbooster cards in two computers. As a test I put the router and computers in the same room and copied a 170 MB file from one computer to the other. It took 85 seconds which works out to be 2 MB/sec ( 16 mbits/sec).
I would have expected double this rate but am I being optimistic?