I have this cooler and my E4300 OC to 3.0Ghz with no problem.
You'll need a case with good air flow.
Make sure the temps don't go too high.
Overclocking is safe as long as you're carefull not pushing the CPU too high over its limits. What's dangerous with overclocking is if you give too much volt to your CPU.
The PSU must be a very good brand with stable 12v rails.
I thought that buying a new cpu will be more subtle... I am looking at Q9550(quad core 2.8 GHz). Only thing is that I don't know if my zebronics realwatts 500W pro series can take it. Right now with the XFX gts 250 core 1 gb and e4300 things r goin smoothly.
here is the info on the psu, graphic card and cpu..