TYLERisMiSfIt :
damn i have a new motherboard too :/ so what should i do then?
New HDD, new motherboard = new install.
You can install it from your existing media. You have 30 days to activate it.
It almost certainly will not activate. You may or may not be able to convince MS to allow that same license on the new hardware. At the very least, you'll have to go through the phone robot to activate. You may have to call and talk to a human. But it is entirely up to them.
But the preinstalled OEM license states that your current OS license is for that original motherboard.