No votes have more power than third party votes. Like I said, the third party candidate is either so close to the other parties that their one or two differences aren't enough to gather a majority (remember, not everyone thinks like you and no everyone will think those differences are important enough to vote outside their party) or they are so different from those parties that they appear like loons.
We have had that conversation since before 96 too. Ross Perot took enough voted from Bush that Clinton could legitimately claim he won by the highest margin in 50 years and not even get half the votes in the popular vote.
But you are ignoring the biggest problem. Until third parties take state and local elections and garner the same types of support that the two parties have, they will be absolutely powerless if the win. I mean seriously, one third party senator, what is he going to do? You need so many supporters to get a law onto the floor, so many more to have anything done with it. So in comity, which because the parties take care of their own usually based off seniority, they will be in low level committees, with low ranks. Again, what can they do? Vote no on something everyone else will ensure passes? Big whoop.. Suppose a third party candidate gets elected president, he has no support in congress, it will be just like Carter's administration when he decided he was going to clean up congress and even his own party abandoned him and voted to pass laws he vetoed.
Like I said, until the third parties actually invest the grass roots efforts and gain the support, they are a waste of voted. Better to infiltrate and change from within. Better to do the tea party thing seeing how the vast majority of positions that will crop up, you will already be in agreement with the major parties (one of the other). Corrupt and co-opt those who will lend you support from within.
*and by corrupt, I don't mean dirty illegal stuff, I mean convince them your way is better so they abandon the party line or change the party line to your way. It's easier to do when you are one of them and have their ear.