Is your computer up-to-date?
To use Snow Leopard, make sure your computer has the following:
Mac computer with an Intel processorFind out if your current Mac has one of these processors by clicking the Apple icon at the top left of your screen, then choosing About This Mac.
5GB of available disk space
1GB of RAM
DVD drive for installation
If your computer does not meet these requirements, you will need to upgrade your computer before using Snow Leopard.
Want to upgrade your OS?
To upgrade to OS X Lion or OS X Mountain Lion, make sure your computer has the following:
Mac App Store
If you are running Snow Leopard v10.6.5 or earlier, Mac App Store was not included. Therefore, you will need to buy the Mac OS X Snow Leopard v10.6 DVD from Apple Online Store and install it. Then you may upgrade to OS X Lion or OS X Mountain Lion.
If you are running Mac OS X Snow Leopard v10.6.6 or later, Mac App Store is included, and you may upgrade to OS X Lion or OS X Mountain Lion anytime.
OS X Mountain Lion is only available through the Mac App Store.