If you keep breaking spokes and you're "just riding along", I would say that the wheel truing is not exactly top notch. I would try the place across the street. Explain to them what has been happening, your riding style, etc. and see what they say. If you're really heavy and tend to sprint alot, that might have something to do with it, but it sounds like a bad wheel build. The only time I break spokes is when I crash...