You forgot the number after the decimal in "2.GHz" lol.
I had an Nvidia 8200M asus board a while back with that CPU. I was able to increase the FSB alone and get it to 2.6GHz... I think it was unstable and I had to lower it to 2.5GHz or something. So my FSB was at 250 and my ram (a pair of mushkin silver) was at 1000. I didn't need to apply more voltage at all either. I was using a stock cooler.
Can you adjust the North Bridge multiplier or the ram multiplier? What are your current settings for your overclock right now?