upgrading 2007 imac?

Would definately suggest you consider Upgrading your OS to Snow Leopard...

Check that your Mac meets the System Requirements here...

Snow Leopard Specs:

http://support.apple.com/kb/SP575

Purchase Snow Leopard,

Mac OS X 10.6 Snow Leopard

4 gb is fine it can always be upgraded. To lion and it works wonderful defiantly worth the 30$. What kind intel core do u have.

I wouldn't bother unless your computer can boot the 64-bit kernel, a requirement to install and run 10.8. See the following: OS X v10.6- Macs that use the 64-bit kernel - if your computer isn't on the list you can't install 10.8.

You can upgrade RAM to the maximum your computer model can accommodate. For the 2007 iMacs that may be 4 or 6 GBs. However, if you are expecting something special to happen, it won't. Neither Snow Leopard nor Lion will make your machine faster.

Buy mountain lion.

ML cannot install on a 2007 iMac because it doesn't have a 64-bit EFI ROM and cannot boot the 64-bit kernel which is a requirement of ML.

Ok

Adding RAM won't make your computer run faster. Only a faster computer will do that. More RAM just makes it possible to run more applications concurrently without running out of memory. Running out of memory makes a computer sluggish. See:

About OS X Memory Management and Usage

Reading system memory usage in Activity Monitor

Memory Management in Mac OS X

Performance Guidelines- Memory Management in Mac OS X

A detailed look at memory usage in OS X

Understanding top output in the Terminal

The amount of available RAM for applications is the sum of Free RAM and Inactive RAM. This will change as applications are opened and closed or change from active to inactive status. The Swap figure represents an estimate of the total amount of swap space required for VM if used, but does not necessarily indicate the actual size of the existing swap file. If you are really in need of more RAM that would be indicated by how frequently the system uses VM. If you open the Terminal and run the top command at the prompt you will find information reported on Pageins () and Pageouts (). Pageouts () is the important figure. If the value in the parentheses is 0 (zero) then OS X is not making instantaneous use of VM which means you have adequate physical RAM for the system with the applications you have loaded. If the figure in parentheses is running positive and your hard drive is constantly being used (thrashing) then you need more physical RAM.

Adding RAM only makes it possible to run more programs concurrently. It doesn't speed up the computer nor make games run faster. What it can do is prevent the system from having to use disk-based VM when it runs out of RAM because you are trying to run too many applications concurrently or using applications that are extremely RAM dependent. It will improve the performance of applications that run mostly in RAM or when loading programs.

That is not true. I'm typing this on a 2007 iMac running Mountian Lion and I did nothing special to get it to run. Mountian Lion requires a Core 2 Duo which is a 64-bit processor, or better. As a matter of fact, 10.8 makes my computer feel brand new. It's really fast on it.

That being said, 10.8 it's likely the last OS that will run on it.

Macs that can be upgraded to OS X Mountain Lion

1. iMac (Mid 2007 or newer)
2. MacBook (Late 2008 Aluminum, or Early 2009 or newer)
3. MacBook Pro (Mid/Late 2007 or newer)
4. MacBook Air (Late 2008 or newer)
5. Mac mini (Early 2009 or newer)
6. Mac Pro (Early 2008 or newer)
7. Xserve (Early 2009)

Now this is the info I was looking for. I'm on a Mid 2007 iMac myself (looking to upgrade my iMac to the latest rev this year - 5 years is a good run for a desktop system, in my opinion, particuarly one that has had exactly one upgrade to 6 GB of RAM), and was wondering what the performance was like.

Anyone else on a Mid 2007 iMac care to weigh in?

For anyone interested, my prior iMac was a 2002 (iLamp, 15" screen, M8535LL/B for you geeks out there), so I got 5 years out of that one as well, topped out with 10.4. It's glitch? Optical drive failure. But an external drive solved that for me.

Can't wait to see the new iMacs . . .

That was my question as well. Thanks for askingand posting the most helpful reply. I have an iMAC mid 2007 with 2Gigs of memory. I upgraded to 10.6 and loved it, all the way upto 10.6.8. With Lion it slowed down to worse than a PC! I upgraded to Mountain Lion, no better. I wish I could downgrade to 10.6.8 without losing my data. I would apreciate any help in downgrading to 10.6. If I understood correctly, using Time Machine will restore everything including the OS (10.8 in my case). I guess it's the spinning beach ball for me until I ge a new MAC..

You and I have the same machine except I have 4GB of RAM and Mountain Lion is fast enough to make my computer seem new again. Spend $50 and get 4GB of RAM.

I have a late 2007 imac with 4G RAM and my iMac runs slower after upgrading from Lion to ML.