World governments

I was just thinking about what we would do if ever we succede in making this world a maxim of our ideals. What if we finally "win" right, how do we preserve our new found utopia..or whatever . If we resort to the tendancies that we are use to I suspect that all would eventually return to its corrupted, infected, controlled state. We smell a world government brewing. If it ever did emerge on the scene it would probably kick it off with a world dictator...or soon there after. My question is this, would a world government be the solution to the problem posed before. If we succede in "freeing" the world how do we protect it from falling back into evil. Would a variant of the UN then be the solution , with legeslative powers as well as the ability to enforce a system of checks and balances? ,yet representitive of even the most disennfranchised. How do we then have it mediate through the many peoples without picking up an ambitiouse dick-tator along the way. I wonder if there is any way to preserve somethings purity. At the very least a world government would be able to distribute our resources evenly or appropiately. As well as prvide a forum for the world to have its issues adressed and decided upon. I wonder how if we model it after our most sincere ideals that it wouldnt end up like the demonic extreme we are lined up for.