61,857,928 votes for Kerry
49,942,157 votes for Bush
1,441,478 votes for Nader
How did I come up with such (rather nice) numbers?
First, I took the popular vote from 2000: http://www.fec.gov/pubrec/fe2000/prespop.htm (giving Bush's numbers to Bush, Gore's numbers to Kerry, and Nader's numbers to Nader)
Then, I looked at this poll I'm always quoting: http://www.worldpoll.com/press_room_wppk_qr.phtml
Following what it suggested, I first took 14% of Bush's numbers and gave them to Kerry, then I took 5% of Gore's numbers and gave them to Bush.
Then, using Ross Perot as a guide (comparing his 1996 results with his 1992 ones), I chopped Nader's vote in half. I gave one quarter to Kerry, and threw away one quarter (people who won't vote this time or who will vote for Cobb).
Then, since Karl Rove said there were 4 million evangelical Christians who failed to vote in 2000, and he's putting out the GOTV to get them, I gave Bush that 4 million.
Since our side's GOTV are rather insane, too, I multiplied the result I had for Kerry by 110%. Not unrealistic, I don't think-may even be conservative.
There you go. Note that even if you give Kerry zero votes from Nader, AND assume our GOTV doesn't work at all, AND still give Bush his four million, Kerry is still up by over five million votes, merely from the 14% vs. 5% crossover vote differential.
I hope I did all my math correctly. :)