the problem is election fraud, not voter fraud.
even if every single voter presents valid identification, and every single voter is verified as eligible to vote, those things are ultimately meaningless...less than meaningless, actually.
manipulation of the 'vote counting' software is real.  go to 'blackboxvoting.org' and read up on the subject, especially regarding the gems vote count software.  watch 'hacking democracy' while you are visiting the website.
until every vote is cast on a paper ballot, and each vote is hand-counted and cross-checked (machines could be best used to verify the tally), which of you is certain that your vote was counted as cast?
ask yourself why it is that these machines and their proprietary software are so deeply entrenched in our electoral process.  ask yourself why there is such adamant resistance to reforming the process.
cui bono?