The software you need is Windows.
You basically set the power button to put the PC into hibernate. Your PSU will simulate the press of the power butting after 1min, putting the PC into hibernation. When you turn the key and the PC boots, it resumes from hibernate.
There's dozens of threads about this and a writeup int he FAQ Emporium. There's no need to start a new thread, unless you're too lazy to do a little research. And then, there's still no reason, but you get flamed.