Upon the advice of a friend I decided to get high-gain antennas. This is much simpler than moving the router to a more central spot because of the number of ethernet cables that would have to be moved.
I checked the LinkSys site, Googled places to buy and then realized that I had to know the model number of my router so that I would get the correct connector. So I picked up the router and turned it upside down to get the model number and then put it back. For some reason or other I didn't place the order then.
Later I went downstairs and noticed that the signal on my laptop was strong! Apparently moving and putting it back place the existing antennas in a more favorable position. To remember that positioning for the future I will take a photo.