How important a role does the personal computer (be it desktop or laptop) play in planning and/running your games?
Indispensible - I would have a seriously difficult time running my games to my own level of satisfaction without my computer.
Heavy Reliance - Game notes, maps, dice rolling - I even use it to look up rules on PDF's of the rulebooks, though I still bring my hardcopy books to game and do stuff manually.
Equal Weight - Fully half of the tasks that were once done manually (map-making, dice rolling, plot outlines, NPC stats etc) are done by a computer.
Periodically - I might make some notes on my computer because it makes writing faster, or I might put some pictures on the screen for my players to see, but that's it.
Call me low-tech if you want, but a pen, some paper, my books and some dice is all I use.