Well 50 Ft is abit to far to hook the PC to the TV Directly.
You could get the Video signal there using HDMI/DVI, but you would run into the problem of controling the PC remotely.
Wireless Keyboards & Mice usualy have about a 15' range at best.
Getting one that works on RF is going to cost more money too.
USB can't go that far either w/out powered repeaters every 8 foot or so. There are devices that let you push USB 1.1 signals over ethernet cable, and back to USB for 50+ feet though, but not cheap.
LCD Tvs and LCD monitors are totally different monsters.
As someone who uses a PC as my "Tivo" (MythTV) I'd say this.
Check your TV and verify it has either VGA, HDMI, or DVI inputs.
VGA would be the easiest, since the TV will do the scaling for you from VGA to its Native resolution. If you don't have VGA or DVI, but you do have HDMI (Note: HDMI & DVI are interchangeable with simple cables. HDMI Just carries an Audio stream as well), you will need to get a Cable that changes DVI from your PC's Video Card into HDMI for the TV to support. Assuming you are using windows, you will then have to set an appropriate resolution to have your computer "talk" to the TV. DVI/HDMI is a bidirectional signal, your TV actualy tells your Computer what its capable of, and your computer should adjust acordingly. however its been my experience this doesn't work as well as its supposed too. Mostly because basic TV displays operate at very different resolutions then computers. Widescreen makes things even worse. Usualy you can get a picture, but its "fuzzy" to read, and doesn't match up properly. They are getting better though, so if you have newer equipment it may be plug and play.
Best solution is whats been said here. Get a used PC (or Laptop) and hook it up directly via VGA or HDMI/DVI, and try to tweak it.
Just don't go with an intel based video card. Find a System with an ATI or Nvidia.