wxman--
the linksys, in essence, IS a hub... well, it's a switch actually, but a switch is just a smart hub working in layer 2.
getting peer to peer working right in windows is sometimes tricky. but there's nothing you need to set up in the linksys configuration. the gateway/router setting isn't related at all. it deals with whether that router is on the edge of a network or inside it.
can you ping the ip addresses? For instance, open the MS-DOS prompt, and type ping xx.xx.xx.xx where that is the IP of your other computer. I am assuming you are using internal IPs dynamically assigned from the DHCP server inside the router (this is the default). So your computers will likely be 192.168.0.100 and 192.168.0.101. Try pinging one from the other.
Assuming you get a reply (which you should if your networking cable and router and nics are working). Next thing to do would be to go to Start-->Find-->Computer and type in the name or IP of the other computer on the network and see if that finds it.
Often the problem with Network Neighborhood is that computers don't always show up there. But the Find Computer function always works for me. Then once you're there you can see the shared folders and then just map them as drive letters.
hope that helps.
l2c