Plasma won't pick up wifi, too far, options?

Use the TV Ethernet port on something like this. The performance is normally much better than any wireless solution but depends on how old is your electrical wires and the way they are distributed. Buy from Amazon or other place with easy return, It works great 90% of the cases but you never know.

http://www.amazon.com/ZyXEL-PLA4205kit-HomePlug-Powerline-Wall-plug/dp/B005GCSZD6/ref=pd_sxp_grid_pt_2_2

WiFi

You could always just setup a repeater for your house so the side of your house that gets lesser performance gets better coverage.

Other options: Make sure you and your neighbors aren't crowding around the same wifi channels.
If you are and nothing is really clear/available get a dual band sim broadcast N router and a 5ghz N adapter for the tv. (*the 5ghz band is typically a LOT less congested since hardware for it is less common atm. However if the router doesn't simultaneously broadcast in 2.4/5 it won't handle the older b/g devices.)

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About Powerline

How this works:
Your setup stays exactly as is right now except 1 free ethernet port on your router is sent through a powerline adapter through your home copper. The TV (in this case) would have another powerline adapter by it to covert back to ethernet which you would plug into your tv.

It "can" work if you have acceptable wiring in your house.
Edited by Tolken - 1/29/13 at 2:52pm

Your current setup stay as is. Just plug one ethernet cable from one of the adapters to your router and one Ethernet cable from the other adapter to your TV. Everything else will work the same. From my experience, when you have wifi signal problems is very difficult to make it work. Repeaters can help but you need good speed and normally anything between the router and the device will cause a gain of signal but a loss in throughput ( speed in this case).
You have nothing to lose, buy it, test it and return if it doesn't work. As I said, most people are happy with this solution but sometimes it doesn't work due to wiring conflicts or too old installation.

I use also this "wireless extender" to provide signal to my mobile phones and tablets. It does work , signal is strong but speed is cut by half.

http://www.amazon.com/Netgear-Universal-WN3000RP-Wi-Fi-Extender/dp/B004YAYM06/ref=sr_1_3?ie=UTF8&qid=1359500558&sr=8-3&keywords=wireless+extender

You can try one or the other or even both, always possible to return if they don't work. I would try the powerline first.

Repeaters drop your thru-put in half.

Powerline might work better if you can't run a cable. But I'm not sure how the speed compares with WiFi.

If this is FIOS, then another option would be MoCa, ethernet over cable. This is how the STBs get their information. If you have a cable outlet in the room, then you can get a MoCa adapter and get an Ethernet port in your bedroom