stock cooling will severly limit your final speed.
i have seen some at 4.0ghz which is extreme, but on stock you should get to about 3.4 ish.
a lot will depend on your motherboard and cooler but.
this is a very basic explanation of overclocking
its basic maths. your e7500 is rated at 1066mhz. you always divide this number by 4 so 1066/4= 266, this is your fsb. (or cpu frequency)
then your processor (cpu) has a multiplier of 11 (it may say cpu clock or ratio)
so 266 x 11 = 2930mhz or 2.9GHz
boot into bios and disable C1E, and any other energy saving settings.
unlink your ram, so it stays at stock speeds, you can overclock the ram later
can you raise the fsb?
try rising it to 280, press f10 (usually) to save new settings
boot into windows
download realtemp and coretemp (google them)
install and run them
then download Intel Burn Test (ibt) and run it.
have a look in task manager and notice how much free ram is listed.
in ibt set threads to 2 (for 2 cores) and then click on custom ram and enter an amount just below the free amount.
eg. i have 2520mb free ram. so i enter 2500 into the custom ram.
run the test for 5 passes. for now,
keep an eye on temps (do not let it go over 80.c) or in realtemp, notice the distance to tjmax, never let it go less than 20.
stress testing is extreme, in day to day gaming your temps will be about 20.C lower.
if test runs fine, go back into bios, and change frequency (fsb) to 300 and repeat the tests.
keep doing this in 20mhz steps until windows will not boot. then just go back a step (remove 20 from the fsb) to the last stable frequency,
just raise the cpu voltage a couple of levels. it should now boot.
its a balancing act, higher voltages will get you higher fsb, but it will also give you higher temps.
the E7500 is fine upto 1.39v.