Just purchased Mountain Lion and now realized it wont work on my 2008 iMac, tried to start a chat but Apple support chat says my serial

Question

I also tried to see if I could buy memory but find thatI cant even do that with this relic?

Answer 1

Those models will support:
Maximum Memory
6.0 GB (Actual) 4.0 GB (Apple)
Memory Slots
2 - 200-pin PC2-6400 (800MHz) DDR2 SO-DIMM
They should be upgradeable to Mavericks as well as Mountain Lion.
Upgrading from Snow Leopard to Lion or Mountain Lion to Mavericks
To upgrade to Mavericks you must have Snow Leopard 10.6.8, Lion, or Mountain Lion installed. Purchase and download Mavericks (Free) from the App Store. Sign in using your Apple ID. The file is quite large, over 5 GBs, so allow some time to download. It would be preferable to use Ethernet because it is nearly four times faster than wireless.
     OS X Mavericks- System Requirements
       Macs that can be upgraded to OS X Mavericks
         1. iMac (Mid 2007 or newer) — Model Identifier 7,1 or later
         2. MacBook (Late 2008 Aluminum, or Early 2009 or newer) —
             Model Identifier 5,1 or later
         3. MacBook Pro (Mid/Late 2007 or newer) — Model Identifier 3,1 or later
         4. MacBook Air (Late 2008 or newer) — Model Identifier 2,1 or later
         5. Mac mini (Early 2009 or newer) — Model Identifier 3,1 or later
         6. Mac Pro (Early 2008 or newer) — Model Identifier 3,1 or later
         7. Xserve (Early 2009) — Model Identifier 3,1 or later
To find the model identifier open System Profiler in the Utilities folder. It's displayed in the panel on the right.
Are my applications compatible?
         See App Compatibility Table — RoaringApps.
Upgrading to Lion
If your computer does not meet the requirements to install Mavericks, it may still meet the requirements to install Lion.
You can purchase Lion by contacting Customer Service: Contacting Apple for support and service - this includes international calling numbers. The cost is $19.99 (as it was before) plus tax.  It's a download. You will get an email containing a redemption code that you then use at the Mac App Store to download Lion. Save a copy of that installer to your Downloads folder because the installer deletes itself at the end of the installation.
     Lion System Requirements
       1. Mac computer with an Intel Core 2 Duo, Core i3, Core i5, Core i7,
           or Xeon processor
       2. 2GB of memory
       3. OS X v10.6.6 or later (v10.6.8 recommended)
       4. 7GB of available space
       5. Some features require an Apple ID; terms apply.