One of the most frustrating things about becoming a digital artist is that most people you show your work to just don't quite understand what it takes to create anything using a computer. Everyone has picked up a pencil or a crayon and they understand the dynamics of how that works. You push the pencil against the paper and make thick or thin marks to show the representation of an observed object or idea.With a computer involved it seems to become a mix of magic and sentient machines that make exactly what the artist wants.
This is not true.
If anything the computer art/drawing programs fight against you most of the time. If you are using a tablet like mine: Intuos 5 then you are staring at the screen and moving your stylus pen according to what you see on the monitor. There's a bit of a disconnect and you have to train your hands and your eyes to work together.
If you are using a mouse, then you are crazy and there is no hope for your wrists and your inevitable carpal tunnel surgery. I'm joking, but seriously, get a tablet. It can be a Bamboo too, just get off that mouse. /soapbox
I have an elderly MacBook Pro and it has battery issues. It has a better video card than my husband's Air so I plug it in with a giant orange extension cord and make it work until the wee little fan sounds like a small jet taking off. Hot weather is hard on digital art computers since they run hard and hot anyway. I've been accused of abusing my machine, which is named GLaDOS, but I try to give it a break every hour or so. Breaks are essential for your fingers and eyes too. I try to use a standing desk, but I'd rather be sitting and concentrating on art rather than how much my feet are hurting.
Share your set up! What do you use and why? Are you a sitter or a standing artist?