The stock heatsink will NOT be enough. You will need a big cpu cooler to keep the temps in check. Look at the Noctua D14 and D15 along with the Phanteks and Deep cool cpu heatsinks.
The best software to use is no software at all. You need to overclock via the motherboard bios. If you did not already know this, I suggest researching as much as possible before attempting to overclock. Its not something to just jump into and learn on the way.