XBB- Nice summary and its on the mark. In our current system it takes mucho $$ to run a campaign. So at the practical level the Independant, Green, and other parties while often having superior ideas and plans, cannot raise enough cash to be a market itself as a contender.
That said we must focus on the big two and holding each of them accountable to their promises. Yes, change is in order starting with eliminating earmarks, favors to lobbyists, drawing district lines, you get the idea.
The tax code is one of the main tools they have to exercise control. If we were ever able to convert to a simple flat tax that would be a great step in removing the power they wield.