I had to last week, and was none too happy with the process. I was under the impression Time Machine would restore your drive to the state it was in from whatever backup you chose....ummm, no. It restores your apps and that's it. Once booted you can use the normal Time Machine interface to go back and restore documents, music, movies, etc. It was a complete pain in the @ss. It in no way restores any system prefs, app registrations (I spent hours hours trying to find various serial #s), or even any email settings. I couldn't even restore email messages to their respective accounts....I had to go in and sync with .mac to get the account settings back, then re-import the messages from the backup. I also had to go in and reauthorize all my iTunes purchases. I like the overall idea and the user interface for restoring the occasional accidentally deleted file, but as a true backup, it stinks.