I've already install a dual-boot verison of ubuntu on my windows 8.
When I launch my computer, I don't see the grub, it launch windows 8.
During the launch of the computer I can press 'esc' so I get on the windows 8 interface for boot selection and I can select 'ubuntu' and then I see the grub and I can choose ubuntu.
So it works, BUT it's a long way to simply boot on my ubuntu partition.
My question is, how to automatically start on the grub and not on windows 8.