Associate
Vertical resolution is the one thing you're short of on all but the highest-res widescreen displays. Why wave goodbye to a chunk of it for the Dock when there's plenty of room at the side?
Yeah, but the dock work's best at the bottom. A lot of programs when maximised use the space behind the dock when its on the sides.
And in leopard the dock just looks wrong on the side.
As long as you have the size nice and small it takes up very little space.