bit of a mess

I have MacPro with 2x2.8 quad-core with 4 hard drives, the original OS on a 600GB HD.
I have just bought latest Snow Leopard and when it loaded it told me that the original HD did not have enough room as I had partitioned it to include Windows on Bootcamp. So I loaded Snow Leopard onto one of the 2TB back up discs.
I have lost all items in my itunes library and all items on the desktop which included access to 3 stand alone back up HD's. So I would like to access those items.
Secondly as I now want to get Mountain Lion i could download it onto the 2TB HD, but it occurs to me that if the OS is a stand alone would it be better if I took the old 600GB HD out, put a new 2TB HD in, load the Snow Leopard onto that and use it for all subsequent uploads?
Or could I load Mountain LIon directly onto the new HD?

So I loaded Snow Leopard onto one of the 2TB back up discs.
I have lost all items in my itunes library and all items on the desktop which included access to 3 stand alone back up HD's.

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So, have you installed SL onto the 2TB drive and then booted the Mac from that drive? If you have, I would think that you should be able to use Migration Assistant to transfer all your files and settings from your Mac to the other drive.

Again if you've booted from that 2TB drive, the other externals should still show on the desktop. Check in Finder Preferences and see if the option to show them on the Desktop is ticked.

Yes, I can not now get into the original OS as it will not open in Restart and pressing Option. I assume that as that partition is filled it can not open. I have now accessed the hard drives by ticking the box you mentioned but when I go into Migration Assistant it only seems to be geared towards another computer, so I can not get it to work from one HD to another. Going back to the Desktop I can now see the HD's but no other information that I had stored on desktop for convenience. Also as I can not now get into the original partitioned HD with the OS on I can not access the Applications on that drive.
I have tried increasing the size of the partition with the earlier OS but as it is the
lower partition I can not seem to be able to increase its size. I have reduced the size of the other partition so as to enable me to be able to increase the lower one, but it will not let me increase its size?

when I go into Migration Assistant it only seems to be geared towards another computer, so I can not get it to work from one HD to another.

Click to expand...

Hmm...it certainly works between a Mac and an external, maybe not for another internal.

Can you boot from the 600Gb drive, transfer stuff to one of the other drives, then boot from SL drive and then access the other drive?