The question is not "was the election stolen?" but "was it secure"? In this post 911 world, we can easily make the distinction between "nothing went wrong, today" and "something could go wrong". What we will find, regardless of whether there is a way to make it add up to enough votes to swing the results, is to prove that there are pervasive irregularities in the balloting system, that these pervasive irregularities favor the Republican Party consistently, and that the "solutions" proposed often make the situation worse not better.
Given that there were so many irregularities in the conduct and tallying of this election, why was Kerry, whose theme campaign theme song was "No Surrender" so quick to concede? Why has there not been a louder call for investigation? Here is an interesting stab at an answer. The argument is basically that it makes more sense strategically to call the results into question after the Fallujah assault has run through the news cycle. I don't know if I agree entirely but it does make compelling reading.
Note: Had to edit this three times today in order to weed out grammar and spelling errors. What the hell is wrong with me?