I have been using Time Machine to backup my iMac since Dec 07. My iMac just had a hard drive failure this week which was replaced under my Apple Care warranty. Time Machine worked perfectly and restored 99% of my system. I do not run TM every day because I download some very large technical Podcasts that I have transferred to iTunes so I can listen on my ipod. They are renewed every day and I delete them every two weeks or so. That being said, each one is about 500MB and I would fill up my TM if I backed up every day. I now only have 40GB free of my 500GB drive. Since my system is up and running as I would like, I was thinking I could just reformat the TM drive and make TM start over, making it's first initial backup and move forward from there. Does that make any sense? Or should I just let it keep backing up until I run out of space and let it delete the older backups. Curious what the best practice is.