Upgrading to a Hard Drive with OSX pre-installed

[toast19]

Is it possible to upgrade to a hard drive that was used previously on a different Macbook without having to format it upon installation?

 

[mulo]

yeap, it will boot right up if the hard drive has mac installed

 

[alphaod]

Depends. If the older hard drive has the right drivers or not; if it's running the latest version of OS X, it's more likely it'll work; on the safe side, I would suggest an Archive and Install after putting the old disk in. That way you retain your applications and files, while getting the correct drivers installed.