Cely D's are great overclockers. I have a 2.4 478 socket running at 3.6 on air. It's just a prescott with less cache and lower fsb. just cranking the fsb from 533 to 800, i didn't really even have to raise the voltage. 36c idle about 51c full load. still not a great proc, but it gets what it needs to done. If he has a 1.8 p4 tho he'll need a new motherboard to, so by then you might at well by an AMD 3000+ or 3200+