What is the difference in resolution and quality between SCART, VGA, and HDMI? For my old MacBook (2,1) I have a mini-DVI to Video adapter that I use to connect to the TV (mini-DVI-to-Composite-to-SCART). It works, but I cannot seem to get the right resolution for the TV display (no wide screen resolutions available at all).

I see there are other options to connect to as well on the TV: VGA and HDMI. How do each of these options perform differently in terms of resolution and quality?

For example, I'm planning to buy a HDMI adapter and would like to understand if this will make it possible to use a wide resolution for the TV from the MacBook.

I'd be very happy if someone can give a detailed explanation what resolutions and qualities each port is capable of.
First: The maximum resolution of your TV is important. Your TV have probably a resolution of 1920 * 1080 Pixel (FullHD).


  A (Mini) Display Port can display about 3840×2400 Pixel
  
  VGA is an older standard, an was created for an Analog connection
  between devices.
  HDMI was created for a Digital connection.


So, the HDMI option is the best, because HDMI fully supports FullHD resolution. 

VGA could probably be display FullHD or HD Ready (1280x720 Pixel), but it's not recommended.

So, the best decision is to buy an Mini Display Port - to - HDMI Adapter.

It is hard to give a detailed information of the cababilities of each Video-Output, because there are many differnt version of each one out there.