Currently Being ModeratedNov 5, 2012 2:20 PM (in response to RebeccaW)
If your Mac has a Core 2 Duo(not Core Duo) or better CPU, you need to phone the online Apple Store and order a Mac OS X 10.6 DVD and a download code for Lion. If you don't know what CPU it has, choose About this Mac from the Apple menu.
Currently Being ModeratedNov 5, 2012 2:24 PM (in response to RebeccaW)
Yes, you understand correctly. However, to upgrade to Lion you will need to first upgrade to Snow Leopard 10.6.8. Neither is available in Apple Stores nor from the App Store. I recommend that you not upgrade Tiger to Snow Leopard. Instead I recommend you backup your current system. When the Snow Leopard DVD arrives boot from it, then erase your hard drive and do a clean install of Snow Leopard. Upgrade that system to Lion after you download it. Before you install Lion make a copy of it in your Downloads folder.
You can purchase Snow Leopard by contacting Customer Service: Contacting Apple for support and service - this includes international calling numbers. The price is $19.99 plus tax. You will receive physical media - DVD - by mail.
After you install Snow Leopard you will have to download and install the Mac OS X 10.6.8 Update Combo v1.1 to update Snow Leopard to 10.6.8 and give you access to the App Store.
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.
Be sure your computer meets the minimum requirements:
Snow Leopard General requirements
1. Mac computer with an Intel processor
2. 1GB of memory
3. 5GB of available disk space
4. DVD drive for installation
5. Some features require a compatible Internet service provider; fees may apply.
6. Some features require Apple’s MobileMe service; fees and terms apply.
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.
Make Your Own Mountain/Lion Installer
1. After downloading Mountain/Lion you must first save the Install Mac OS X Mountain/
Lion application. After Mountain/Lion downloads DO NOT click on the Install button.
Go to your Applications folder and make a copy of the Mountain/Lion installer. Move
the copy into your Downloads folder. Now you can click on the Install button. You
must do this because the installer deletes itself automatically when it finishes
2. Get a USB flash drive that is at least 8 GBs. Prep this flash drive as follows:
a. Open Disk Utility in your Utilities folder.
b. After DU loads select your flash drive (this is the entry with the mfgr.'s ID and size) from the left
side list. Click on the Partition tab in the DU main window.
c. Under the Volume Scheme heading set the number of partitions from the drop down menu to one.
Set the format type to Mac OS Extended (Journaled.) Click on the Options button, set the
partition scheme to GUID then click on the OK button. Click on the Partition button and wait until
the process has completed.
d. Select the volume you just created (this is the sub-entry under the drive entry) from the left side
list. Click on the Erase tab in the DU main window.
e. Set the format type to Mac OS Extended (Journaled.) Click on the Options button, check the
button for Zero Data and click on OK to return to the Erase window.
f. Click on the Erase button. The format process can take up to an hour depending upon the flash
3. Locate the saved Mountain/Lion installer in your Downloads folder. CTRL- or RIGHT-click on the installer and select Show Package Contents from the contextual menu. Double-click on the Contents folder to open it. Double-click on the SharedSupport folder. In this folder you will see a disc image named InstallESD.dmg.
4. Plug in your freshly prepared USB flash drive. You are going to clone the content of the InstallESD.dmg disc image to the flash drive as follows:
a. Double-click on the InstallESD.dmg file to mount it on your Desktop.
b. Open Disk Utility.
c. Select the USB flash drive from the left side list.
d. Click on the Restore tab in the DU main window.
e. Select the USB flash drive volume from the left side list and drag it to the Destination entry field.
f. Drag the mounted disc icon from the Desktop into the Source entry field.
g. Double-check you got it right, then click on the Restore button.
When the clone is completed you have a fully bootable installer that you can use without having to re-download Mountain/Lion.
Note: The term Mountain/Lion used above means Lion or Mountain Lion.
As an alternative to the above (you still have to do your own download of Lion/Mountain Lion) you can try using Lion DiskMaker 2.0 that automates the process of Steps 2 through 4.