Confused about reinstalling iMac OS

Hi gang-
I work in the music industry here in Nashville, and both of my Macs are used primarily for audio work.
I have a May 2010 Macbook Pro 13" that I have no problem with, I have all of it's original disks and it came with Snow Loepard

Here's my issue- I bought an 20" iMac (2.4 C2D, 4GB) in February of 2009 that came loaded with 10.5 Leopard. I have all the original iMac install disks.

-I've never reformatted the HD, and its way past due. It's a little sluggish & bloated, and I'd like to do a fresh install of the OS and all my software, especially Pro Tools etc.

-When Snow Leopard came out, I bought & installed the upgrade to my iMac, but I think the disk I have is one that will only install on a computer loaded with Leopard (?)

Ideally, I'd like to completely clean off my iMacs internal drive & do a "new from the factory"fresh install. I have a Time Machine backup of my files, so I was thinking I could use disk utility to do an overnight 7-pass erase of the drive in Target disk firewire mode from my Macbook Pro.


My question is, if I completely erase the hard drive for a fresh install, is my Snow Leopard disk going to allow me to install to the iMac, or is it going to tell me I need to have Leopard installed first?

I really don't want to install Leopard from the original iMac disks just to be able to install Snow Leopard if at all possible.

-Is there any way around any of this? Or do I have to search & buy a Snow Leopard full installer disk?

-Additionally, I need Snow Leopard currently instead of Lion because all of my audio software is not yet Lion compatible. But since the Lion upgrade installs on top of Snow Leopard, would I *REALLY* have to install Leopard/SnowLeopard/Lion on my iMac once everything is Lion compatible?? That just seems like WAY too complicated..

Thanks for any advice you guys & gals can give!

Lion is a download from the App Store (unless you purchase a Mac with it already preinstalled ) so you have to have Snow Leopard prior to upgrading to Lion (also unless you have purchased Lion on the usb drive which I'm not sure that Apple is selling yet or not) There are several articles out there about how you can create your own Lion usb drive which is fairly easy and what I would recommend doing once you can upgrade so you can fresh install Lion. Here's a link to one of the articles How to make a bootable Lion install disc or drive | Macworld As far your question about the version of SL you have, I'm not sure (maybe someone else will know this) I would think if it was meant to be some type of upgrade only disk you may just need the full retail version of Snow Leopard.

My question is, if I completely erase the hard drive for a fresh install, is my Snow Leopard disk going to allow me to install to the iMac, or is it going to tell me I need to have Leopard installed first?

Click to expand...

The Snow Leopard upgrade DVD will do a clean install without Leopard being present. However, the upgrade DVD is missing iLife and several other included applications that are normally pre-installed along with OS X. If you have the Snow Leopard full box set, that's not a concern since everything is included.

Thanks, chscag! That makes sense. Luckily, I also have my iLife & iWork discs, and of course I'm assuming I can also pull in apps from my Time Machine backup.
So I'm gonna start the process tonight.. Kind of a pain, as I'm sure it will tie up the day tomorrow when you consider downloading updates & such. Will let you guys know if I run into any snags..

I have a question too

I have tried to fix my 15 mbpro, with a snow leopard DVD i got from apple, but when i try to start the boot sequence (c), it beeps three times. and keeps repeating. I even tried to do the Command+R for recovery and was able to wipe out the the drive. Snow Leopard won't install tho. how can i get it to work?

Better to start your own thread JAlfaro and not hijack another's.

Who knows as you have not provided information about your computer. Maybe it came with Lion pre-installed and did the SL disc come with another machine? if so it will never boot a different machine.