I am looking into the differences between
DVI-A cables, DVI-D cables and DVI-I cables.

Why would anyone buy a DVI-D cable if a DVI-Integrated cable can transmit Digital or Analog? If you ever wanted to connect a VGA monitor, the DVI-I cable would come in really handy, right?

When using a graphics card capable of DVI-I, how do you specify analog or digital output? I don't think both are available at the same time on the DVI-I port, are they?