Hi, So earlier today i bought a Samsung 840 Evo 250gb from Amazon and i am pretty sure on this, but can i use the same activation code again, as the OS is tied to the motherboard? Is this correct?
If preinstalled, it is indeed tied to that motherboard.
If it is a Win 8 that you bought and installed, you can reinstall on whatever hardware you want. 1 PC at a time.
If you have a retail W8 copy (i.e. have the install discs) then there will not be a problem. An OEM copy should also be ok (I don't think the license is tied to anything but the motherboard).
If all you are doing is moving your OS from an HDD onto the new SSD then you can greatly simplify the process by using imaging software (e.g. Acronis True Image / Norton Ghost). Simply disconnect the HDD and restore the image onto the SSD. Running Windows Experience Index then optimises Windows for the SSD. It's also the easiest way to make regular backups.