Tech Gurus, I need help with my wireless network.

Okay, so I have a Cox cable modem and a netgear wirless N router.

For years everything worked fine with the Router excatly where it is now, and the modem in the kitchen with a Cat5 running through ceiling to router.

And it worked great, got a signal to my furthest room and the garage 55' behind the house.

Well I re-did my network, moved where the coax came in and all to streamline it.
I put router next to modem near the TV and receivers and then internet wireless got to be really buggy.

So now I have a older G router that feeds all my wired stuff, I have the N router being fed off of that, both at the same frequency. (I was told to do it like that) I get great wireless downstairs, except in the far off guest bedroom. So I added a cat5 through 115v deally. That runs wired internet through the common on the power.

Or something like that.

Now that room gets great internet.

But then the master is still getting crappy wi-fi.

I'm fixing to run cat5 to it directly but I would really like a whole home wi-fi solution.
My house isn't all that big. But the wireless is at the far bottom right of the house and the room not getting wifi is at the top left.

What can I do to extended wireless?

Also is running two routers a bad idea?

I realized I fell way behind the times with wireless.

I can run beautiful wired networks and have cat5 going in the attic already and am about to run security camera wire/

But looking for ideas to improve system.