totally irrelevant to whats going on now.. but sora.... the drop from 90 to 65nm isnt what affected overclocking.. if anything the pentium 4's overclocked higher than the conroe's.. i think they pentium record is at almost 8ghz.....
the only way the die drop could possibly affect overclocking, is by its lower temperatures.. but it won't be a massive headroom for overclocking
lets compare these 2900pro's to the xt's... from 90 to 80.. does my pro overclock more than an xt.. no... goes just as far