Don't be fooled by pure clock speed. In most of the benchmarks, the Celeron lags big time behind the Pentium 4. The reason is the smaller L2 cache on the Celeron, which has to get by with typically, 128 kB. Not only did the Celerons have to get by with a smaller L2 cache, but their FSB clock speed was also slower. Now with the newer Celeron D, everything is much improved including the FSB. Being a simplified version of the Pentium 4 (Prescott Core), Celeron D still does not support the HyperThreading technology, which is basically a simulation of two logical processors on one single material processor. Celeron is just plain cheap...just as the phased out Durons and the newer Semprons are for AMD. It will always lag behind the Pentium 4 for that reason. Budget CPU.
