Some TVs don't fully support VGA or DVI even when it says so on the tech specs. Even using a DVI to HDMI adapter, the picture can look pretty bad because the Mac outputs 480p, 720p, 1080i or 1080p but most 720p TVs actually have 1366 x 768 pixels and do pretty bad at upscaling 1280x720. If you have a HDMI ínput that also says "DVI" on it (most Samsung TVs have that) use that, then your Mac can do all the scaling and output at the TV's native resolution. This basically gives you 768p which is especially nice when downscaling 1080p, viewing pictures or whatever you do when you hook up you Mac to a TV.
Couch computing (aka sitting lazily on the couch and doing stuff on the laptop) is so much better when you have a huge display and wireless keyboard and mouse.