I have a Intuos3 6x11 tablet, which I use for EVERYTHING I can use it with. As in everything that does not go funk with a mouse, such as FPS games (generally use mouse for games which have wasd+mouse setup or something like that), and certain 3d software such as Wings3D which does not like absolute position input.
So yeah, using the tablet for everything including general navigation in Windows.
I would not say that a mouse is inadequate but I am A LOT faster with a stylus and it feels more natural. People who say that they are more steady with a mouse, yes that can be true, but you can always zoom in or use snapping or something like that. It never has been a problem for me.