The reason businesses use T1 lines vs. Ethernet (Fast, Metro or Gigabit) is because of the differences between these two services. Fast Ethernet refers to the internal network traffic whereas a T1 line is an external to internal network connection. While it may be true that many companies are offering options like fiber to the home, which offer speeds significantly faster than T1 lines, T1 (and its siblings like DS3) still offers many advantages.
If you are a home theater newbie and you are used to the average television set, then a home theater receiver may be a new addition to your vocabulary.