The whole V Brake vs Canti thing is a whole additional can of worms.
It's been my experience that even really cheap cantilever brakes can be made to work well, but they might take a lot of adjustment. Cheap V brakes will always be lousy though.
I'd put my vote for an overhaul; new cables, housing and a new par of Koolstop brake pads will do wonders for your stopping power.