I just got my iMac, and during boot-up for the first time, it asked me if I wanted to transfer my stuff. Naturally, I said yes, and transferred all my setting, apps, etc. Now my iMac is also known as "myname's computer". When backing up to my external HD, it will just rewrite over my periodical TM backups I do on my MBP. How do I rename my iMac so TM will save a separate backup on my HD? As you may already realize, I have my new iMac always hooked up to it, and once or twice a week I unplug the HD and attach it to my MBP for manual backups. Please advise.