Option / opinions on use for an older iMac

Which model iMac?

CLICKY CLICK--->http://support.apple.com/kb/HT1758 How to identify iMac models

Your iMac can be certainly upgraded.

Your iMac model can be upgraded even to the latest OS X 10.9 Mavericks.

When upgrading system software, these are paid upgrades involving installation discs or paid downloads.

If you are using OS X Software Update feature to check for system "upgrades", this doesn't work.

Software update for OS X only looks for system "updates" like from OS X 10.5.7 to 10,5.8.

It won't look for system "upgrades" like from OS X 10.5 to OS X 10.6

These are new OS X upgrades that you need to pay for. They are not free.

If you want to upgrade your OS X version to a more recent one! you need to start by purchasing and installing OS X 10.6 Snow Leopard found here.

http://store.apple.com/us/product/MC573Z/A/mac-os-x-106-snow-leopard

Before installing, make sure you backup all of your important data to CD/DVD, USB flash drives or external hard drive/s before you begin.

After the initial installation of OS X 10.6 Snow Leopard, you can THEN use the OS X Software Update feature to update your OS X version to OS X 10.6.8 and all of the other Apple related software.

Updating to OS X 10.6.8 will give your iMac access to the Mac App Store where you can decide if your want to continue upgrading your iMac to OS X 10.9 Mavericks.

Also, your iMac model can take up to 8 GBs of RAM.

My recommendation is to upgrade the RAM to the max. 8 GBs.

Correct and reliable Mac RAM can be purchased from online Mac RAM sources Crucial memory or OWC (macsales.com).

Good Luck!

To answer your original question, no. To echo what others have posted, you can buy 10.6, update to 10.68 (if the install disk is not already 10.6.8) and you'll then have access to the App Store. It might not be a bad idea to upgrade to 10.8, as 10.9 is not supported by some 3rd party software compared to 10.8. But the better question is why are you looking to upgrade your OS (not that you shouldn't be, just what are you looking to do?)

Most likely NO some had a video out which allowed the use of two monitors but NO way of using the existing screen without a double e degree and a solder gun

I have a related question. I'm buying a used iMac 24 (early 2009). It currently has Mountain Lion installed. I will be migrating data from a Macbook Pro that is running Mavericks. Should I upgrade the iMac to Mavericks before migrating data, or after?

My gut feeling is to take the iMac to Mavericks, then use the Migration Assistant to migrating data from the MBP.

Either way probably won't matter much, since most of the data will be user accounts.