You need knock down drag out dependability, you need to get where you're going. Big things i've found to give me trouble, inadequate wheels, tires and rear drive trane in winter, lube is a big thing, I use pro-link it seems to give me less drivetrane noise and more chial life than the rest. Get a good bag and become god friends with small plastic bags, they will assure that what you put in the bag comes out dry. Good luck with your commuting, Do it, it's a great thing to do.
Pete