Startups vision is not what is taught to MBAs. The giant corporations need a vision to collect disparate chunks of a wide-spread business. Startups use vision as "the cool idea." It is the inspiration that gets the business started. Like the proverbial snowball that begins to grow as it rolls down the mountain slope, startup vision begins with an "Aha!" and expands from there.
Examples are in the current wave of articles written about the Web2.0 wave. A good article was in Business Week's cover story , Valley Boys, of August 14, 2006. It is about people with visions for cool new enterprises: Valley Boys - Business Week . As you read it, you can sense how there was typically an individual who had an unexpected insight to an opportunity and need. That person became the founder of the new enterprise and expanded from that first idea to build a business (very rapidly).
As you read about new enterprises, note how the founders' ideas are very focused on solving a specific problem. They are not ideas about generalities or vague concepts. There is something very practical about the entrepreneur's vision. Yes, it is big and filled with a dream aspect. But it is also very practical, backed up by immediate plans for how it will be delivered, very quickly. That is very different from how big companies think.
BOTTOM LINE: Give your first idea a test: does it qualify as a vision? Is it for solving a big problem? Is it practical? Is it focused? If yes, continue. If not, reconsider. A good vision becomes a cool idea and the foundation for going forward with your new business.