While you did get it working, can I offer a suggestion for the future?
Unless you actually needed to add a NAT layer to the connection (and, there aren't too many valid reasons to do that), ICS isn't what you wanted. ICS is not a bridge - it's a NAT gateway, not unlike a router.
A network bridge (which is just a simple passthru connection - you know, a bridge
) would have been the more appropriate choice.
It's easy to set up, too - just select both network adapters (in Network Connections) > right-click > Bridge connections.
And, if you have equipment on each side of that Win7 box that you want to be able to talk to each other (thru the Win7 box), you might want to change how you have the connections, well, connected.
Keep the DHCP server disabled on the Netgeat router, though, lest it have the same battle with your '54G that it previously did with Windows' own DHCP server (that ICS enabled for the LAN connection.)