After posting the above, I unplugged the router and modem and let them sit 10 minutes, then replugged. This seems to have done the job--the signal is now strong. Thanks to me for talking myself through the issue :)!

Well done! It's always the first choice to do that. Had that not worked the next thing is to uninstall the Wireless network adapter as shown in device manager and reboot, that exercise will reinstall the wireless adapter.

Yes, rebooting the router occasionally will help to maintain the strength of your wireless signal. But what about the security of your wireless router? How do you know that someone else isn't also using your wireless signal without your knowledge? Hopefully, you are using WPA2 encryption instead of WEP on your Linksys router. If you're not sure, check back here. Folks here can walk you through the process.

You could experiment with setting your router to a different channel. If you are currently using 1, 6 or 11 it's likely that others are using those same channels and you could be getting interference from them. Try 3-4-8-9 and see if it makes a difference.

nearand west, tell me more please. How do I find out what encrypton I'm using on my router? I don't want anyone using my wireless signal. . .

little free program called
MetaGeek inSSIDer
shows all your neighbors wifi signals and channels they are using.... and encryptions too... that are used nearby your wifi.

then you can pick a spot that has the weakest neighbor signals or nobody else uses. For least interference.

Here is a link that might be useful: http://www.metageek.net/products/inssider/

Mikie, I installed that program and it is kind of cool, although I'm not sure I know how to use it well or interpret it. I see my fellow condo systems (one upstairs, one down) and the next door neighbors (several condos there too). I do see that my system is on the same channel as my upstairs neighbor, channel 9. Assuming this means I'm getting interference from his (I don't know how to tell?) how do I go about changing the channel? I'm just not sure how to interpret the graph as the "lines" representing my system and my two up-and-down condo neighbors intersect at many points (the other condo neighbor is on channel 6). I don't want to screw anything up as I have an older Linksys router that is no longer support except for a fee.
As to security I have WPA-Personal. For my older router there is no option of WPA2-Personal (I guess).
Thanks for all your help.

WPA is fine usually in your condo setting.

Set or change the channel usually in the router settings.
Then, most computers will automatically show you available networks.. choose your own router name and it matches the channel.

I like to change my router SSID name to something other than the Default manufacturers name.. Like MikesWifi.. then my neighbors know thats mine, and deal with it or me in a neighborly way.
And I always change the router access password to my own secret.. because of the one evil neighbor kid that loves to create havoc. And a nice secret passphrase there helps avoid him too.

marita40: You mention that you have an older router. What is the model number of your router? Find it on the back or the bottom of the router. Also check to see if you can get to the interface of your router. Here's how:

In your internet browser window, type the following:

192.168.1.1 and then hit ENTER. (Do not type "www", just the numbers and dots) Your Linksys router interface should appear on your screen. If you can get that far, the rest is a breeze. This process will enable the most security available for your router. Try it and let us know. If you can get that far, we will finish the process. If not, we can go to Plan B.