While we do have some info on overclocking (well more like a lot), this is the best forum to actually look at:http://www.tomshardware.com/forum/forum-29-347.html
Specifically this thread:http://www.tomshardware.com/forum/240001-29-howto-overclock-quads-duals-guide
As to your question, the E7500 can easily reach 3.6GHz but you will want to make sure that you have proper air cooling. See this site:http://www.frostytech.com/
Specifically this part:http://www.frostytech.com/top5heatsinks.cfm
That site is good for finding the best heatsink for cooling your CPU.
You also want to make sure you use good thermal grease. Artic Silver 5 is normally considered the best thermal paste:http://www.newegg.com/Product/Product.aspx?Item=N82E16835100007&cm_re=AS5-_-35-100-007-_-Product
And here is how to apply that thermal paste:http://www.tomshardware.com/forum/252942-29-some-notes-applying-thermal-paste-xigmatek