Disconnected

The only thing more annoying than being on antibiotics that you absolutely cannot drink any alcohol with (that would be me for the next week or so...) is my wireless internet connection sucking mad donkey balls. It has always been terrible, but acceptable in a dial-up throw back kind of way. Now with the heat (even with AC it's hot here) and maybe the router dying, I can't do much at all. I guess that's for the best as I was trying to take things easy and not get riled up.

Anyways, all you computer smarties out there here is my issue and I would love some ideas on what is best to do:
-Mother in law has a Mac computer and the in-law apartment is diagonal across from my den where my computer is
-When Comcast installed the wireless the inept guy had no idea how to handle a Mac, so we had to allow the MIL to have the direct connect while I got stuck with the wireless
-It does not work at all, sucks
-Offer best ideas to get a new setup, I was leaning towards hiring GeekSquad but it gets complicated with the Comcast hardware I think. Maybe I am wrong, please advise.

Have a good night.

Computer Genius Wanted

Rare Sunday night post, but I have a maddening issue that maybe someone out there can help with!

New Computer Same Story
On Saturday I bought a new computer. My wireless connection at the house was pretty bad, and my computer was 5 years old. I thought an upgrade might just be the ticket.

The computer works great, and the wireless receiver is an improvement over the old one. Still I did buy the Linksys PLTK300 powerline system.

The system works by channeling the router signal through the electrical lines. I then plug into an electrical outlet and hook up a adapter which then runs to my ethernet port.

I set it up and after some hand wringing, the thing worked amazing! I had a direct line with great speed and no drop outs. I was in heaven!

This morning I woke up and turned on the computer. The thing does not work. I can "see" the powerline is working, but I cannot use the line to get on the internet and there seems to be no way for my computer to be able to figure it out. NOTHING happened overnight for crying out loud so I have NO IDEA why it does not work now.

What drives me nuts is the product is so new I cannot find any real help online about it.

So here is my favor should you know anything about computers, networks, and wireless systems;
-Why is my PLTK300 not working all of a sudden?
-How can I upgared the wireless network? What is the best way? I have to have the router upstairs, so I need a good signal all over the house.
-Is there any way to have two modems?

Any help is appreciated.

Have a good night.