Low siganal strength coming from router

I have a Linksys Wireless-N broadband router. I purchased this router last year and for the first year everything was fine. I have 2 laptops an a PS3 that I run off of it. My computers still run fine but their signal strength is low. As I type this I only have 2 bars on my meter. My PS3 however only has a 7-20% that fluctuates continuously. So much that I can't sign in to the EA servers. Nothing has changed in the house. We haven't rearranged or added any new electronics. Please any input would be greatly appreciated.

Download this utility and install it on a laptop.
http://www.xirrus.com/library/wifitools.php

Monitor your router signal for fluctuations or problems.

You can check the airwaves for strong signals from other access points that may be interfering.
Could be you need to change the channel on the router.

Microwave ovens and cordless phones can cause interference also.

A customer of mine had handheld "G" devices that did not work well with a "N" router I installed.
I turned off the "N" stuff in the router and the "G" signal was strong and problem free throughout his location.