The first election was not "fixed", but when it came out so close, and Florida fell into confusion about a recount, the republicans sent in a team of "cheaters" who did exactly that, causing even more chaos. The result was the appeal to the courts, and to the Supreme Court, who at that point wisely denied letting the decision fall to congress. Bush was not elected, he was appointed by the court. This has been well documented.
In the second election, there were very serious flaws and deliberate manipulations by a very pro-republican character in Ohio (the man that designed and sold Ohio their new electronic voting machines, which left no paper trail to recount), that were simply swept under the rug without review because Bush was then the incumbent, and had the power to make those question go away. So it's quite likely that his re-election involved republican cheating as well, though we will now never know for sure.
But none of this cheating would have been effective if the vote had not been so amazingly close. And the vote will not be so close in this upcoming election. So I don't believe that the attempts at cheating, if they occur, will have any real effect on the next election.
However, our electoral procedures are seriously messed up, and we need to rebuild them from the ground up. And sadly, if this rebuilding were to occur, you can bet that both sides would be doing their level best to "fix" the new structure in their favor. Or at least in favor of incumbents. It's frustrating that such cheating has become the normal mode of behavior in government, and that as a result we can't trust our own government to do anything for the good of the people, anymore. And I don't know how to change this.