Sorry, I misread that and mis typed sorta. FSB is important, but L2 cache does alot of work as well, I'd say the northwood. However FSB is the (correct me if i'm wrong) connection point between the system devices and the cpu. If the FSB is slower on a 'faster' cpu, this could hinder performance.
Newer isn't always 'better' in this case, if there was a drastic price difference and you were on a budget it would shift the choice, but realistically it sounds like this isn't the case. Also, you keep saying the 'newer' prescott when it lacks HT. Again, I might be wrong, for a newer processor the prescott doesn't look all that appealing.