1700+'s are like playing the lotto.. They can range from 2.0ghz stable, to 2.5+. Look for the DLT3C (low voltage 1.5V) JIUHB's. The DUT3C (standard voltage) have also been shown to overclock decent. Without having these steppings (for instance if you happen to get a T-bredA), you are pretty much dead in the water.
2100+ B's generally hit 2.3 without problems, 2.4 isn't out of reach, but if you get past that, consider yourself very lucky. I have yet to see a 2100+ that couldn't get to 2.25 - 2.3ghz stable. AIUHB's are the ones with the greatest overclocking potential. Again if you get a T-bred A you are out of luck, as 2ghz seems to be the max for those processors.
2500+ generally hit 2.2ghz without problems. 2.4 is rare, but many have hit that stable. 2.2 is pretty much all-day, but you would have to add voltage (and adequate cooling) to obtain those speeds or higher. There is currently no "magic" stepping that is a great improvement in overclocking above all others, so if you were to order one, you are almost guaranteed to get at least a "decent" o/cer.
