The threat of voter fraud is very real- especially in non-presidential election years (NPEY's). In those years, voter turnout is less than 38%. To win, a candidate needs 19% of the voters to vote for him/her. Watch how candidates work special interest groups in NPEY's. They will promise crazy things to small groups in order to get the 19% they need. People that are involved in special interest groups would tend to vote at a higher percentage of those not involved in a special interest group (I have not looked up to verify, but the logic certainly would indicate this to be true).
If only 38% of voters turn out, you could do what this guy at the beginning of this thread did and have a greater than 60% chance of not getting your vote (or votes) thrown out.
If everybody would exercise their right to vote, it would make voter fraud a little tougher. On the other hand, if you don't care enough to vote, then you are a dumbass and should leave the country.