To upgrade from OS X 10.5.8, you must first buy Snow Leopard by calling the phone number in the Apple Online Store: 800-MY-APPLE (in the US). Snow Leopard costs $20, or $30 for a five user license. Do not obtain Snow Leopard from any source other than Apple.
Make sure your system meets Snow Leopard's requirements:
To install Snow Leopard for the first time, you must have a Mac with:
- An Intel processor
- An internal or external DVD drive, or DVD or CD Sharing
- At least 1 GB of memory (RAM) (additional RAM is recommended)
- A built-in display or a display connected to an Apple-supplied video card supported by your computer
- At least 5 GB of disk space available, or 7 GB of disk space if you install the developer tools
If your system does not support Mountain Lion's requirements, you may be able to upgrade to Lion. To do that you must call Apple again to order a download code. Redeem the download code in the App Store to download Lion.
Make sure your system meets the requirements for Lion:
Mac OS X 10.7 "Lion" System Requirements
- Mac with an Intel Core 2 Duo, Core i3, Core i5, Core i7, or Xeon CPU
Core Duo CPUs are not sufficient for Lion
- 2GB of memory (RAM)
- OS X v10.6.6 or later (v10.6.8 recommended)
To determine which Mac you have, what kind of CPU it uses, and how much memory is installed: > About this Mac