Unduly Noted

Don’t throw that old 802.11b router out. If you have the ability to run a long ethernet cable to or near the end of your house that has a poor signal, you can extend your network without purchasing a branded “wireless access point”
How To:
Run a 25 or 50ft cable from one of the ports (labeled 1-4 if it is a 4 port router) of your main router towards or as close to the problem area.
Do not plug it into the old router yet.
Plug your laptop into the old router (port 1)
Check your documentation on how to logon to the routers configuration page. (Typically 192.168.1.1 or 192.168.2.1 are the most common, type either one into your web browsers address bar. Common default passwords can be found here)
Once logged in check to make sure this routers IP isn’t the same as your main routers IP. If it is, change the last number in the series (pick something in the 50’s should be fine)
Now still in this old router find the DHCP setting and turn it OFF. Your router will reboot (again if you had to change the IP above)
Still in the old router go to wireless settings and change the wireless name (the name of your wireless network) to the exact same name of your main routers wireless network.
ALSO: change the channel of this wireless network to something different from your main router. Typically 11 is the default so you should be safe changing it to 6 ot 7.
Now plug that long cord from the main router into one of the 1-4 ports of the old router.

Now if your laptops are set to get an IP automatically you will be all set to go, just give it a bit to establish that initial connection and get an IP (it takes a little longer than normal)
If you are having trouble resolving an IP feel free to manually set your IP address on your computer with the main router’s IP in the router/gateway box.

Your computer should now automatically switch to whichever signal is better without you having to do anything.