Wireless network speed question (a bit technical)

I can only get about 800kb/s on network file transfers. One machine is reporting between 18 and 48 mb/s connection speed, the other 54. I understand only half that figure is possible, but task manager shows this low level of utilisation.

What gives? Is this all I am gonna get? I’ve changed network channels, forced G mode, and the one machine is only 1 room away from the router. I’ve even added a D-link wireless router in place of the wireless function of the Orange Sh*tbox.

How are you doing the transfers?