I'm not really sure which duron you should get now, but i'd have to say get anything as low speed as possible to overclock. From reading on this board, everybody is getting great results overall with oc'ing the 600-700. I'd go with the lowest speed one ya can find around. With my duron 600, i could hit 1000 by 10x100 no prob at 1.75v. But i found that the best combo was 107x 9, which gave me 963, but only needed 1.625v, and ran very cold. I didn't plan on going any further, until today when i recieved my thermistor, to check to see if my mobo was in fact reading generally the right temp. I found out that my kt7-raid, with the bios wt was reading almost the exact same as the thermistor was touching the edge of the core. So now i have my duron 600 to 1080, running about 40 idle, 108x10, a 1.85v, and i'm not worried about the temps cause they aren't very high for me, just got lucky.
All in all, go with a 600 IF you can find one anymore, they're cheap, and seem to have had the best luck ocing.
balael
My Setup