BAPCo SYSmark 2000 - Windows 98 SE
This chart lines up all results I got during my many days of testing. In brackets you will find the basic Celeron model (multiplier-locked of course) and the clock settings we used. At the bottom are some settings, which did not work stably.
It was interesting to see that a Celeron 366, overclocked to 458 MHz (83 instead of 66 MHz system speed), is faster than a regular Celeron 500. Even more impressive is the Celeron 566, which ran reliably at 850 MHz (at 1.75V). That will give you the same performance as using a Pentium III 667 or 700 - at about half the price!