Ofcourse they won't be substantially faster, but it will boost peformance at least a little. The extra cache when the P4s went Northwood didn't seem to do a whole lot at first, but IMO it probably did the most to save the P4, that and the great overclocking success via the .13 fab process. The P4 definately need that performance boost right out of the box as I'm sure the vast majority of P4s are untweeked. The overclocking success saved Intel in the tweeking crowd as the old P4s weren't very exciting overclockers. AMD kind of shot themselves in the foot stepping up the Athlons. In one fell swoop Intel doubled the L2 cache and shrunk the die of the P4 with great success. On the other hand AMD failed to convert to .13 with the Tbred A barely getting much more than the Palomino could offer @ 2100+ as I believe the 2200+ is the fastest stock retail Tbread A. Needed to fix that AMD pumped out the Tbred B allowing them to step up the clock rate which is what they really needed. Tweekers can now really push the Athlon with the Tbred B with many enthusiasts hitting speeds anywhere from 2 to 3 GHz with 2.4GHz not being hard for most everyone to touch. One problem, AMD still left out the extra L2 cache. Now we need Barton. Intel did in one swoop that AMD is now taking in 3. Kinda sucks, would have been really nice to have seen Barton in the fall last year instead of when we will see it, which is hopefully just a few more days.
AMD has to have some justification in giving a 1.83 Ghz CPU a PR of 2500+ when they also have a 2 GHz CPU with a 2400+ title...