How to tell the speed of an AMD processor Athlon XP started out at 1.33GHz with a 1500 rating, which favoured it very strongly over the equally rated competition. From that point, the Athlon XP increased in frequency by 66.67MHz for each 100MHz increase of the equivalently rated Pentium 4. So an Athlon XP 2200+ is really 1.8Ghz. Here is a table to demonstrate my point. AMD rating_______1500__1600__1700__1800__1900__2000__2100__2200 Actual frequency__1333__1400__1467__1533__1600__1667__1733__1800 Hopes that help you understand how AMD rate their processor. You don't have to think very hard before you realize that the Pentium 4 would eventually catch up to and exceed the performance of its equivalently rated Athlon XP. The release of the Northwood, which performance-wise is basically a Pentium 4 with effectively twice as much on-die cache, closed most of the performance advantage that the Athlon XP had in the past. According to most benchmarks: AthlonXP 1600 perform better than Pentium4 1600, AthlonXP 1800 perform equal to Pentium4 1800A, AthlonXP 2200 perform worse than Pentium4 2200B also, AthlonXP 2200 perform worse than overclocked Pentium4 1600A to 2130(133FSBx4=533) ------------------------------------------------------------------ Benchmarking programs here: http://www.computingondemand.com/phpBB2/viewtopic.php?p=17#17 Info on overclocking Northwood revisionA here: http://www.sharkyextreme.com/guides/hwGuides/article.php/1380951