LCD is a type of display, where as HDTV is basically the quality of the picture (high def vs standard def).
You can connect your PC to your TV usually using composite, S-Video, VGA, DVI, or HDMI. The connections will vary based on your TV and video card.
LCD and Plasma TV's are thin and somewhat light, vs tube TV's and projectors. If your TV is less then 4-5", it's most likely an LCD or Plasma.