upgrade from 10.5.8 to 10.6
My iMac won't let me upgrade to 10.6 from 10.5.8
Apple Event: May 7th at 7 am PT
My iMac won't let me upgrade to 10.6 from 10.5.8
How to Install OS X Updates Successfully
A. Repair the Hard Drive and Permissions:
Boot from your current OS X Installer disc. After the installer loads select your language and click on the Continue button. Then select Disk Utility from the Utilities menu. After DU loads select your hard drive entry (mfgr.'s ID and drive size) from the the left side list. In the DU status area you will see an entry for the S.M.A.R.T. status of the hard drive. If it does not say "Verified" then the hard drive is failing or failed. (SMART status is not reported on external Firewire or USB drives.) If the drive is "Verified" then select your OS X volume from the list on the left (sub-entry below the drive entry,) click on the First Aid tab, then click on the Repair Disk button. If DU reports any errors that have been fixed, then re-run Repair Disk until no errors are reported. If no errors are reported click on the Repair Permissions button. Wait until the operation completes, then quit DU and return to the installer. Now restart normally.
If DU reports errors it cannot fix, then you will need Disk Warrior (4.0 for Tiger) and/or TechTool Pro (4.5.2 for Tiger) to repair the drive. If you don't have either of them or if neither of them can fix the drive, then you will need to reformat the drive and reinstall OS X.
B. Make a Bootable Backup Using Restore Option of Disk Utility:
Destination means the external backup drive. Source means the internal startup drive.
C. Important: Please read before installing:
D. To upgrade:
Purchase the Snow Leopard Retail DVD.
Boot From The OS X Installer Disc:
E. If updating:
The only iMacs you can upgrade to 10.6 from 10.5.8 have an Intel CPU and at least 1 GB of RAM (768 MB or less won't cut it). Read this tip on other pitfalls:
https://discussions.apple.com/docs/DOC-2455
Since you are updating to 10.6, if it is possible to get yourself up to 10.6.8, it is highly recommended, because of a recent malware, which only is fully patched in 10.6.8 or 10.7.3 and above. Otherwise disabling Java in your web browsing is strongly recommended. This tip explains your options:
upgrade from 10.5.8 to 10.6