Whichever side won in 2000, it would have been done by fraud. The Republicans happened to win, but if the Dems had gotten a chance to guarantee themselves a win (even if through illegal methods) they would have.
I think both sides commit some fraud at a relatively low level. Honestly, I think Democrats have been much more effective at perpetrating vote fraud because they tend to control things in centralized urban areas with a lot of votes, while Republican strength tends to be spread across a large number of suburban/rural jurisdictions, and major fraud by Republicans would require a great deal more coordination among different parties than would major fraud by the Democrats.
In addition, virtually all the places with reputations for major vote fraud (i.e., Chicago) are under iron-fisted Democratic control.
As far as Florida 2000 is concerned, it was such a confused mess that any number of things contributed to it. The networks calling the state for Gore while the heavily Republican panhandle was still voting surely depressed the Bush vote. Gore's vote was most likely depressed by the Palm Beach County ballot. There were many other things I'm sure, some small scale fraud by both sides and some screwups.
What I found most funny that not a single Republican that I ever heard of came forward to claim he/she intended to vote for Bush, but made a mistake. Could that be possible? My theory is that Democratic voters are trained to blame everybody but themselves for their mistakes, and therefore came out blaming a conspiracy (by a Democratic county-level political hack) for their incorrect vote. A Republican would be embarrassed to admit that he/she was too stupid to figure out how to vote right, and shut up about it.
Gore's team definitely created the impression that they were trying to steal the election by calling for recounts only in heavily Democratic counties.
Nation, you are absolutely correct that the Democrats would have been only too happy to win through fraud if they could have. Probably the Republicans too, but I don't think that's what won the state for Bush.