right now... GF3+ is fine... but P4s are really a waste of money... I hate intel for the P4... the P4 is just a marketing scheme. if you ran a P4 and a P3 at the same frequency, the P3 would outperform it... though a P4 northwood would be closer.
they found a way they could actually slow down the processor, so that they could run it at a higher frequency more stable. is that good? not really, but it lets them sell things with bigger numbers on them, and dumb consumers always like bigger numbers.