Not necessarily true. The Clock for Clock speeds on the AMD chip were much better than what intel offered at the time. And Athlon XP's and 64's walked all over pentium 4's for years.
Intel Pentium 4 540 / 540J 3dmark 03 score 799
AMD K8 Sempron 3400+ (rev. F2, 59W, CW) ->741
AMD K8 Sempron 3400+ (rev. E6, socket 754) -> 645