My potential with Zalman 7000? (noobish)

[secretweapon]

This is my first attempt since the old celeron days. What kind of oc speed can i expect with a zalman 7000 cpu cooler? (see my sig) My current setup has all stock voltages, idle of 40 and load of 52 Celsius in windows. memory is set at 2.5-2-3-7. Also will the arctic thermal paste be much better than the one that came with the zalman? Thanks for ur help.