restore using time machine

if you plan to clone your old disk to a new one, better use SuperDuper. With superduper, you will be able to create a bootable image of you system and its files in your external disk. After that, you will be able to boot from the external drive (hold down the option key while booting untill you see a menu which will let you choose from which disk to boot, and chose your external drive). Once you booted from your external, check that everything is fine and that all ur files are there. Then, replace your old hdd with your new one. While booted from the external, open up Disk Utility, choose the new hdd u installed and click on the "erase" tab. Choose "Mac OS Extened (Journaled)" as format and give it a name (you will be able to change that in the future so dont think alot about it). After formatting your new internal disk, run superduper again, and now clone your external to your internall. Reboot, hold down option key again and now choose your internal disk. Thats it

IMPORTANT: While backing up with superduper: SuperDuper needs to use a whole disk to make a bootable image. That means that it would erase the stuff on your external disk. What you can do is, copy all your files from your external somewhere, and replace them once your done, or if you got enough space in it, make an extra particion, one for your files and one for superduper. Either way i would backup my external drive somewhere before starting the process.

Hope that helped, good luck