Usually the 805 is regarded as THE price/performance killer, good overclocker and overall good performer. PentiumDs are not bad but they're space heaters and if you want to OC them, tou've got to spend $$ on a good cooler.
For more performance, look at AMDs X2s; the 3800+ is good value and the upcoming 3600+ should be even better, priced around $120-130. They can OC at least a 200MHz (10%) on stock cooling, sparing tou the headaches of PD heat.
Another thing for which you should consider an X2 over a PD is C'n'Q, it gets important in a dual core.