Welcome to the Apple Support Communities
First, check if your computer is supported > http://support.apple.com/kb/sp575 Buy Snow Leopard > http://store.apple.com/us/product/MC573/mac-os-x-106-snow-leopard Then, make a backup, insert the DVD and upgrade. Finally, open > Software Update and update to the most recent version
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
After you install Snow Leopard you can decide if you want to upgrade OS X to the latest version, Mountain Lion. Mountain Lion is available in the Mac App Store, which is available to you after upgrading to Snow Leopard.
Make sure your system meets the requirements for Mountain Lion:
Mac OS X 10.8 "Mountain Lion" System Requirements
To install Mountain Lion, you need one of these Macs:
- iMac (Mid 2007 or newer)
- MacBook (Late 2008 Aluminum, or Early 2009 or newer)
- MacBook Pro (Mid/Late 2007 or newer)
- MacBook Air (Late 2008 or newer)
- Mac mini (Early 2009 or newer)
- Mac Pro (Early 2008 or newer)
- Xserve (Early 2009)
Your Mac needs:
- OS X v10.6.8 or OS X Lion already installed
- 2 GB or more of memory (RAM)
- 8 GB or more of available hard disk space
a brody's Mountain Lion upgrade summary, which contains more detail than the above:
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
To determine which Mac you have, what kind of CPU it uses, and how much memory is installed: > About this Mac
- 2GB of memory (RAM)
- OS X v10.6.6 or later (v10.6.8 recommended)
The specified 2 GB minimum is barely adequate for either Lion or ML. They will run in 2 GB but you may not like its performance. 4 GB is a more realistic minimum.
Start with Snow Leopard which you have to have even if you can upgrade further.
1) Make sure your computer meets Snow Leopard technical specifications - http://support.apple.com/kb/SP575 This mostly means making sure it is an Intel Mac and has at least 1GB RAM (at least 2 GB is recommended). Go to the Apple in the upper left corner of any window, then "About This Mac". Does it mention "PowerPC" (not Intel), or Intel? To check RAM continue to "More Info...". It should say you have at least 1GB of "memory".
2) Buy a Snow Leopard disc from Apple online
or telephone Apple. In the USA: (800) 676-2775 (contact information for other countries: http://support.apple.com/kb/HE57)
Alternatively you can buy from online retailers but anticipate paying much more than the original price which is the price still charged by Apple
3) Backing up your computer before upgrading is always a good idea.
4) After installing from the DVD, update your Snow Leopard installation using Software Update or manually downloading and installing the Mac OS X 10.6.8 Update Combo v.1.1 - http://support.apple.com/kb/DL1399
MacBook upgrade possibilities - https://discussions.apple.com/message/19577869 - "The Early 2006 model 1,1 Core Duo can only run a maximum of 10.6 Snow Leopard. The models Late 2006 Core 2 Duos 2,1 through Early 2008 4,1 can only run a maximum of 10.7 Lion. The Late 2008 model 5,1 Aluminum Unibody through the Mid 2010 White Unibody model 7,1 can run 10.8 Mountain Lion."
Kappy 08/2012 post on upgrading to Snow Leopard, then Lion or Mountain Lion - https://discussions.apple.com/message/19401628 - including how to get Lion since Apple removed it from the online store.