Flat Panel, Hang on the Wall-- Plasma or LCD: you will need to purchase a wall mounting kit and have it professionally installed (unless you know a true carpenter). Most retailers offer installation as does the Panasonic website.
Plasma is best for action movies and sports, most won't burn in an image from static pictures like menus or video games any longer, but if you have a video gamer in your house, I'd opt for an LCD-TV
DLP & LCD projection: Less expensive, still excellent picture. Larger and usually cannot be mounted on the wall. DLP is excellent for sports and action movies.
Under 40" -- Your choice is the (CRT) tube TV or LCD flat panel. Size and price will dictate your choice. Recommend that you get a widescreen. Samsung makes a slim design of tube TVs.
Note:"Flat panel" is the kind of thin TV that you can hang on the wall.
"Flat Screen" refers to a flat, not rounded TV tube screen.