I had the same question and you seem to be addressing it:
I want to upgrade to Yosemite. My iMac was built in October 2006. My processor is a 2 GHz Intel Core 2 Duo. I am currently running OS X 10.6.8.
Can I do it?
<Re-Titled By Host>
No.
Your year and model iMac doesn't meet the minimum hardware requirements for either Yosemite or Mountain Lion.
The highest OS X your iMac can be upgraded to is OS X 10.7 Lion.
However since your year and model iMac can only address 3 GBs of RAM, max. OS X 10.7 Lion may not run very well on that Mac.
My advice is that you keep your iMac running OS X 10.6.8 Snow Leopard.
It is the best OS X version for that Mac.
I want to upgrade to Yosemite
