Hi FurryNutz,
Just thought that I should report back and let you know that I have put my router back down into the basement where it originally was. Things are better now, as they were before. Obviously the router was not happy with the long ethernet cable and perhaps it was the issue.
I had read another post somewhere else where someone had hooked two DIR-655s together in order to get their signal to some upper floors. After reading this, I thought to myself, wait a minute I have another router (DLink WBR-2310) that is doing nothing, why don't I try that too. So, I gave the older router a new SSID, a different IP address and put the DIR-655 back down in the basement (nice and close to the Cable modem) and it's now been up (knock on wood) for over two days... and the other router, acting as a simple extender, seems to be doing the trick there too.
Thanks, once again, for all of your suggestions.