Do you really believe that any vote makes a difference? What percentage of the total pool of voters are you? How naive to think that you could make any difference to how this country is run!
You are, to put it mildly, an idealistic fool.
/sarcasm
Of course, voting for a 3rd party candidate does send one very important message. It sends the message that there are people interested in having people from that party in power. Because this fact is often ignored, it is very important that as many of us as possible keep sending this message over and over and over again.
One of the wonderful things about a two party system is that it often doesn't make any difference who wins. They're both stupid jerks who you wouldn't want as your boss, never mind as the leader of the free world. This allows you to ignore the whole republican/democrat thing and let your imagination run free. If you could have anyone as president, who would it be? Now vote for them.
Of course, this sort of voting is voting to change the system, to expand the sort of choices that future generations may someday have, rather than voting to stop the bad guy from winning this time around. Is either candidate really that that bad? Or, to be more exact, that much better? Leave this election to the fools who really care about party lines. We'll win over someday...