Installing new drive in Intel Imac

[jchow]

Thanks for the reply. I understand what you are saying and I've read the user's guide. I've got a couple of stupid questions because I want to get this right the first time. Now that I have an unpartitioned new hard drive in the imac, can I just connect my usb external backup drive, hold down the "option" key when I start the imac and it will boot from the ext drive? Then go to disk utility and partition the new drive and then use the backup- all files option in disk utility to dump the info from the back up to the new internal drive?

-or-

Do I need to use the OS X install disc and run disk utility from the install?

I'm not trying to be dumb, just want to have everything clear before I start.

Thanks