I am surprised you saw any improvement in speed of transfer of the file as I would expect the read (at one end) and write (at the other end) speeds of the devices involved tho limit the speed of transfer.
I thought about that before testing, but both testing machines were quad core processors and I thought this would eliminate most, if not all, slowdown between reading speed on the sending end and the writing speed on the receiving end, thus giving me a better idea of transfer speed increase between machines.
I am only wondering if I would gain anything by installing new cat6 cables. I am pretty happy with the speed increases that I saw just by upgrading the hardware - switches and ethernet cards.
Desktop: AMD 3.6ghz X4, Gigabyte MB, 8GB ram, Multiple PCLOS's, 22.214.171.124-pclos3.pae.bfs
Server: Intel 3.4ghz X2, 4GB RAM, SATA, gnome2, *.pae.bfs, Headless, Servers: LAMP, FTP, Samba, Print, PXE, BT
HTPC: Phenom II X4 2.8ghz, 4GB Ram, 1TB SATA, PCLinuxOS-KDE, NVIDIA N220GT HDMI, *.pae.bfs