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How do I completely clean out/reset/reformat/whatever my Macintosh? I'm talking a deep cleanse here.

I'm willing to look at any free software that may aid in this.

I'm running OSX 10.6.5.

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up vote 5 down vote accepted

Boot the OS X disc that came with your computer, and in the menu bar, go to Utilities -> Disk Utility and select your disk in the left column (e.g. 500GB Hitachi...). Click on the Erase tab at the top, and select Max OS Extended (Journaled) from the drop-down menu. Title your disk (if you want, or leave it as Macintosh HD), and click Erase. Quit disk utility (command + q) and continue with the OS X install as normal.

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Then format it as NTFS, then HFS, then FAT32, and you stand a better chance of the data being much harder to retrieve. – geoffc Jan 2 '11 at 0:09
@geoff If you want it harder to retrieve, click Security Options beside the Erase button and choose one of the three (four?) security options (zero-out data etc.). Guaranteed to be secure. Formatting as different filesystems without zeroing-out data does very little to prevent the data from being readable; it's comparable to changing the cover of a book multiple times: the contents of the book are still intact. – squircle Jan 2 '11 at 0:41
@geoffc please elaborate. I'd say the little administrative file system data doesn't make much difference. Data won't be erased that way. – Daniel Beck Jan 2 '11 at 8:26

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