When I got a new TV 4 years ago and wired everything up I found I had a funny looking cable left over. Thought it was an error so stuck it in a drawer and forgot about it. Last year I mentioned it to someone and he said it was to connect a computer to the TV. Still haven't got round to doing it, though.
HDMI great! Carries video and audio signal. Most tvs but not all Laptops have them.
Plug and play - simple.
Most though will have a VGA socket (so thats a vga to vga cable) but that is for picture only so you will also need a jack to phono lead for sound. (and that will be a jack to RCA or phono as it is otherwise known lead). The jack goes into the headphoine socket on the laptop and the red/white or yellow into the tv input.
Best to source them off eBay and in many different lengths too. High street prices for cables are just silly.