I think Bush's college grades were just slightly better than Kerry's. Bush had C's in the majority of his courses but quite a few B's as well (a couple of courses where he just missed an A). I think if he had been more studious and less involved in extracurricular activities, he would have had a higher GPA. Gore had some A's but also some grades that were lower than any of Bush's grades.
Of course a lot of people today who belittle Bush's college grades forget that they were earned before the days of grade inflation--for the same quality of work he'd have an A average today.