Your setup sounds a little more complicated (to me anyway) than it
needs to be.
Just a suggestion... Buy a wireless/router/switch (something like a
D-Link DI-624), and forget about ICS. They're pretty cheap these days
($80 or so). Assuming your broadband modem has an Ethernet port on it,
just connect it to the WAN port on the wireless router. You can then
connect away with wired and wireless nodes. Obviously, there's some
configuration involved, to suit your needs. But, seems like a cleaner
solution.
If you want to shop around for prices,
www.froogle.com works well
(remember to sort by "Price: Low to High")
Chet