Right, you have got a Linksys router (from post #3). Power off the Set Top Box. Unplug the Netgear and disconnect it from the STB. Connect the Linksys WAN port to the STB using ethernet cable. Temporarily (to enable you to get the setup going) connect a laptop or desktop using ethernet to a LAN port of the router. Power on the STB, let that settle, power on the linksys, let that settle, power on the connected PC. You should now be able to setup the Linksys router (follow the Linksys manual instructions).
The Netegear router previously attached to the STB will be redundant (put is away somewhere).
I don't know whether the MA111 USB adaptor will be resuable with the Linksys based network. It depends if you are able to reconfigure it's receiving frequency and encryption passcodes. Manuals available from
here. Note the MA111 is only 11b speed whereas the Linksys is 11g speed (much faster). Your home wireless network may be slowed by this MA111 being present, although it will be more than adequate for your 1meg broadband.
Most centrino laptops have a wirless adaptor built in. Once you have the wired network established and configured, you should thenbe able to setup the wireless Linksys based network, and enable the laptop's wireless adaptor to get that up and running.