Help with Mac OS X Lion clean install

Question

I have a late 2008 15" MacBook Pro that has Lion installed which was upgraded over Snow Leopard. I have heard that performing a clean install can freshen up the system and is just generally a good thing to do. When I downloaded Lion from the Mac App Store I made a bootable disc because I heard it's something good to have just in case. I have also been backing up to an enxternal hard drive using Time Machine. So I was thinking about doing a clean install but I wanted to make sure of a few things and to get your thoughts on if it is actually a good idea or a waste of time.
I would format my hard drive then restart and hold down the option key, choose to boot from the disc and clean install. Once finished use Migration Assistant to move my data from the external hard drive with my Time Machine back ups and that should be everything done and dusted.
I know I have probably got something wrong somewhere and have maybe even got the completely wrong idea about the whole thing.
I would appreciate any help and advice, thanks.

Answer 1

Install or Reinstall Lion from Scratch
If possible backup your files to an external drive or second internal drive.
Boot to the Recovery HD:
Restart the computer and after the chime press and hold down the COMMAND and R keys until the menu screen appears. Alternatively, restart the computer and after the chime press and hold down the OPTION key until the boot manager screen appears. Select the Recovery HD and click on the downward pointing arrow button.
Erase the hard drive:
Select Disk Utility from the main menu and click on the Continue button.
After DU loads select your hard drive (this is the entry with the mfgr.'s ID and size) from the left side list. Note the SMART status of the drive in DU's status area.  If it does not say "Verified" then the drive is failing or has failed and will need replacing.  SMART info will not be reported  on external drives. Otherwise, click on the Erase tab in the DU main window.
Set the format type to Mac OS Extended (Journaled.) Click on the Erase button and wait until the process has completed.
Quit DU and return to the main menu.
Reinstall Lion: Select Reinstall Lion and click on the Install button.
Note: You can also re-download the Lion installer by opening the App Store application. Hold down the OPTION key and click on the Purchases icon in the toolbar. You should now see an active Install button to the right of your Lion purchase entry. There are situations in which this will not work. For example, if you are already booted into the Lion you originally purchased with your Apple ID or if an instance of the Lion installer is located anywhere on your computer.