its amazing isn't it, how often is this question asked macdude? the first time i ever saw a p-rating i made the assumption that it was the equivelant number of mhz. yes its equal or better than a 2.8ghz prescott.
actually i'm sorry i may have been partially wrong. semprons can't quite keep up with the P4 on stuff like raw processing power when encoding etc but they still excel in games. so on some things the p-rating would better reflect a celeron and on others it would still be comparable to the p4.