so I use my bike (77 schwinn sportabout) for commuting and don't exactly want to let the rain get in my way. it rains enough around here to be something i have to deal for sometimes up to a straight week of on and off rain that leaves the roads in pretty bad shape. I noticed on my first wet ride that between my weight and the bike's, the single pivot sidepull brakes just ARENT enough...they barely do the job.

now since I'm not uber weight conscious, I'd like to go with the most weatherproof option: disc brakes
but what kind of work is involved in converting a road bike to disc brakes? since the fork isn't already built for it, does that mean getting a new fork? what about the rear?

failing that, do dual-pivot sidepulls still only require the 1 mounting bolt?

also, would cantilevers be stronger/possible? (i know i don't have the bosses built on, but how hard is it to add them?)

Your most weather proof option would be a Shimano Nexus rear hub, either in roller or coaster brake configuration. A disk brake in the front would require either a fork change or having a caliper mount brazed on, which would require a repaint of the front fork.

As one of my early mentors once told me: "Anything is possible, it's just a matter of how much money you want to throw at it."