The Prophecy...?

[Halbarad of the Dunedain]

As we all know there is a Prophecy in Star Wars that states that there will be a one that will have the power to bring the force into balance. Qui-Gon Jinn beleived this one was Anakin Skywalker, with the highest meteclorian count ever charted it seems plausable. A Human with more "force" in him than even Yoda himself. My question pretains to the idea of balanced. What exactlly is balance to George Lucas? There was a center for Jedi and the training of almost an army of Jedi. Where as the Sith were supposedly two, no more no less. Although I don't feel this is true as during the apprenticship of Darth Maul Count Dooku must have also been in the service of the sith, creating a paradox of three Sith at one time at least. However, that fact aside, there should only be two, master and aprentice. So, what balance is needed? The destruction of the Jedi till there is only two left? Wouldn't that be balanced?
Within the films we see Darth Vader return to Anakin Skywalker and destroy Darth Sideous creating an equality one Jedi one Sith; Luke and Vader. Then Luke watches Vader die and so the force is still unbalanced! This idea really boogles my mind because it never actually works! Any ideas on the whole Prophecy thing!?