well i depends greatly on your specific cpu and the cooling that you have attached to it......are you using the stock cooler? do you have a good case with alot of airflow? do you have a solid psu? like i said it mostly depends on the cooling you have
Overclocking is never guaranteed. If its your first time, follow some tutorials and good luck. Not sure on the cooling, like drums101 said this is all important. Based on your mobo and CPU tho you should be able to get high 3's - 4.
But DONT quote me on that!! Go careful, increasing your BCLK by small increments until unstable, then do the same with the volts (Vcore and VTT most important). Never go above 1.4v with either.
What mem do you have also that can have a controlling factor on how high you can push your CPU.