Grab a broadband router with wireless
My personal favorites, Linksys WRT54GX (SRX) or Belkin Pre-N

If on a budget a bit more...the WRT54GX2 (SRX200) is like a baby Pre-N router....almost as strong as the big brother GX.

Both are Pre-N/MIMO routers....far superior in getting that signal strength across your house/upstairs/downstairs, etc.

What you'll want to do is turn off your Motorola for at least 15 minutes...so it "forgets" the MAC of the prior device connected to it. Then uplink the WAN port of your new router to it, power up the router, power up the modem...let the modem synch up and "learn" the MAC of your new router. Then cycle the power on the router after a few minutes..and BAM...you should be online (once you set your other computers up to it...at least one wired one for setup).

Then proceed with your other computers, just leave their IP to "obtain automatically".

For the wireless, if you get a Pre-N/MIMO router, you can still use older B and G wireless network cards in your computer and still realize the increased range of MIMO. Recommend sticking with G network cards for better support of WPA security, much easier to setup than the old WEP standards, and more secure. For your Windows XP operating systems, make sure they're up to date with security ,especially service pack 2, which made the wireless configuration utility much easier to work with.