What are the steps for upgrading os x 10.5.8 to 10.6.7

Question

I'm thinking of upgrading from 10.5.8 to 10.6.x.  Can I just install over the top of 10.5.8 or do I need to do something beforehand?  Do I just insert the disk and run?
Much obliged.

Answer 1

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 Installer menu (Utilities menu for Tiger and later.) 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 shutdown the computer for a couple of minutes and then 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
Open Disk Utility from the Utilities folder. 
Select the backup or destination volume from the left side list.
Click on the Erase tab in the DU main window.  Set the format type to Mac OS Extended (journaled, if available) and click on the Erase button.  This step can be skipped if the destination has already been freshly erased.
Click on the Restore tab in the DU main window. 
Select the backup or destination volume from the left side list and drag it to the Destination entry field.
Select the startup or source volume from the left side list and drag it to the Source entry field. 
Double-check you got it right, then click on the Restore button. 
C. Important: Please read before installing
If you have a FireWire hard drive connected, disconnect it before installing the update unless you will boot from this drive and install the update on it. Reconnect it and turn it back on after installation is complete and you've restarted. 
You may experience unexpected results if you have installed third-party system software modifications, or if you have modified the operating system through other means. (This does not apply to normal application software installation.) 
The installation process should not be interrupted. If a power outage or other interruption occurs during installation, use the standalone installer (see below) from Apple Downloads to update.  While the installation is in progress do not use the computer. 
D. Download and install update(s) if updating: 
Use Software Update, or
Download standalone updater(s).
E. To upgrade from an earlier major version:
Purchase the requisite installer package (Snow Leopard for example.)
Boot from the installer DVD.
Choose the install option:
None required for Snow Leopard.
Archive and Install for versions prior to Snow Leopard.