Ask a silly question time - are you using a hub/switch at all? Will the router you get have more than one network port? If not you will need a hub/switch.
As for networking them now - Normal network cards can connect to each other without a hub, when cross-over cable is used. Normal UTP/STP cable doesn't work unless a hub is used in-between connections.
This is my only conclusions I can come to after reading your posts - as both computers can use the cable modem, obviously both NIC's and UTP cable is working, but it will never work directly connecting without cross-over cable. You can find information as how to modify standard cable to make it a cross-over cable, but you will have to decide if it is worth it in the long run (you may need a standard cable again in future or need standard cables for longer durations than cross-over).
EDIT: PS. Ray, you're getting older, beat ya to it.
