The lists for Athlete of the Year and Performance of the Year are quite different...check out the full lists at iaaf.org. Admittedly, there are strange inclusions to the Athlete of the Year lists. Ana Guevara, for one, would have been a top two choice (along with Mutola) in 2003, but she doesn't belong on the 2004 list.
For AOY, most people on middle distance and distance-oriented letsrun will vote for El G or Bekele and for Kelly Holmes. Me, I picked El G and Tonique Williams-Darling. The head to head 5000 win for El G tips it to him over Bekele, as does the rare 1500/5000 double. Don't be surprised if voters from Europe give it to Christian Olsson anyway.