When I set up my wireless network, the signal to my laptop was "very
good" or "excellent" Now, a week later, with the router and laptop in
the same positions, it ranges from "no signal" to "very weak." What is
wrong? When I move the laptop to the same room as the router, the
signal is "excellent."

go into the router administration and navigate to the wireless
settings. Find the configuration values for the wireless channel. It
will be a dropdown list with numbered GHZ ranges. Usually it is set to
6 or 11 by default. It is possible that a portable phone or something
else is using the frequency very close to the routers. you can
expirement with the different settings until you find on that is
clear.

It is also a good idea to do frequent refreshes by powering down and
back up at least once a week. Depending on where you are, you might
have interferce from other routers or appliances. Once a week is good,
but at the least once a month so it can just reset itself.

mike@boxerdogit.com