I have a 2wire Gateway modem/router. I would like to extend the range by 75 feet to reach an outbuilding i use for an office. What can I do?

A couple of ideas come to mind, but basically 75 extra feet could be a problem. It's unlikely that you will be able to extend the range of your present router, but that's the first place to look. The antenna may have a mini-connector on it that unscrews. You can add a 5 or 9 dB antenna to the base unit and push the signal farther.

The problem you face is you might be able to see the signal, but you still can't talk back to it. There are instructions floating around the internet to convert a wireless router to a wireless bridge. A bigger antenna at the Gateway and a router wired as a bridge would get you all the signal as a point-to-point system.

Of course, an industry standard wireless access point, will have a bridge mode. Again, it might be enough to just get one of those and it will be able to communicate with your existing equipment without adding the high gain antenna.

A typical WAP with antenna is in the neighborhood of $90.

Carl