The 2 GHz. Celerons were very nice overclockers because I believe they were all from the "C" stepping or better of the P4 line. You can check that by downloading CPU-z and it will identify the stepping.
You should be able to get an easy 2.66 GHz. by putting the FSB to 133. Follow the P4 overclocking guide sticky note at the top of this forum for the methodology. And as always, watch your temps as you go...
I've never used that board of yours, so you'll just have to see what it'll give you. I have one of these 2.0 chips at 2.9 GHz. FSB 145 MHz. at 1.5 volts on an MSI 845 board.
Mine runs between 50 and 55 C under load at 2.9 GHz. with stock cooling.
What's your board giving the CPU for voltage? You can check it with CPU-z. One of the later 2.0 Celeron steppings had a 1.25 - 1.525 volt rating and if you are at the bottom of that range you aren't going to get much more speed out of it unless you can get to 1.5 volts at least.
I believe there are some pin mods you can look into for VID changes on these Northwood based Celerons, but I have not tried it.