Officially, Apple says the following:
Your Mac must be one of the following models:
- iMac (Mid 2007 or newer)
- MacBook (Late 2008 Aluminum, or Early 2009 or newer)
- MacBook Pro (Mid/Late 2007 or newer)
- MacBook Air (Late 2008 or newer)
- Mac mini (Early 2009 or newer)
- Mac Pro (Early 2008 or newer)
- Xserve (Early 2009)
Note the word "must" in the first line. Yours isn't one of these, so I doubt ML is going to work on your machine.
Seems like you really need to upgrade to a modern iMac.
A mid-2006 iMac is not supported for Mountain Lion. See: http://www.apple.com/osx/how-to-upgrade/
When did you go to the Apple Store? If it was before Mountain Lion's public release, they may have not known about this.
The exception has been traced to Intel graphics display limitations.
Lion is still available if you contact Apple directly.
As I said, these things are sometimes overlooked. That always frustrating when you get misinformed. That's why I always read the fine print myself.
You could still try to argue that you purchased the RAM with this intention and that you got misinformed but it's doubtfull that it will work since it wasn't like if to sold you something that doesn't work on your computer.
Nevertheless, you should really see a speed increase since you were probably only at 2Go which was also the bare minimum for Lion. In any cases, I would suggest that you keep the RAM and wait your next computer that will come with ML.
I didn't buy the memory from Apple Store since they don't carry one for my model. We even joked about them not carrying parts for an older model machine! They really goofed. Oh, well, Mt. Lion does a lot of neat things that I don't have devices for anyway, so I probably don't need it anyway. I just like to keep as current with the OS as possible. I ordered the memory online ~ I needed it anyway as things haven't worked well since I got Snow Leopard. More memory certainly can't hurt, right?
Thanks to everyone for answering my questions.
If you are still under Snow Leopard, you could still upgrade to Lion which will gives you access to many more feature and stay closer to the current OS. Here are the requirement:
Lanny: Thanks for the typo. In fact its Québec.