Rap:

Personally I suggest you get CAT5 well established first and THEN add wireless.

1. Cable Modem to Router
2. Router to Hub
3. As many devices off hub as you want (computers, laser printer, etc.)

The cable DHCP assigns ONE IP Number to the whole net via the cable modem. The router then distributes the traffic to sub-nets using pseudo-numbers for sub-nets.

When you get an Airport device it can plug into the hub and any device with a card should be able to switch off to wireless.

A