Overclocking stopage?

Aight, I decided to stop letting my machine rest and start overclocking it slowly until i reached a decent speed..

system:

AMD Athlon XP 2500+

2 x 256 DDR corsair pc3200 cl2

Abit NF7 v2.0

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Right now I'm at 2000mhz, 200x10, and i raised the core's voltage by 0.25v

Now i wanna know how much I could reach considering i have Vantec AerFlow and supertalent case with great cooling (currently the temp is 33c) and how much should i raise the voltage of the CPU core?

also: what about DDR voltage? and how about memory timing? before the overclock is put it on turbbo and got 6-2-2-2 and now i changed it to optimal and it's 8-3-3-2.5

(those are the alues form top to bottom in the bios and sadly i don't know what they mean..)

ok, that's all the info.. please tell me how far you think i can go.. and what percautions and actions i should take to make the system steady and cool?