All you need is a nice fast hub (probably a switch if you have "the need for speed") as you've got a gigabit router there, or buy a wireless router with more wired LAN ports on it than the usual 4, which is a bit low, but what ya gonna do - like you, I am only a user of these products, not a designer!
At home, I extended my base 4 ports by using an old 8 port 10/100 hub plugged into one of my base ports on my WiFi router... works well to keep my windowz computers sharing files etc between them, but as you'd expect, hardly does anything good for speed if they are all active!!!
Whatever - Just as a starting point....
http://games.dlink.com/products/category.asp?cid=3
What you do is use one of the ports on the wireless router to feed a port on the switch. This is a diagram from the DLINK web site:
http://games.dlink.com/products/resource.asp?pid=494&rid=1893&sec=4
Hope this helps.
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