If Apple will give me my money back I will go back to Tiger. Apple released an unfinished product and covered its ass with legal disclaimers. And Apple commercial is pure disrespect to his competitors and totally unethical. I personally hate it. Looks like yapping doggy.
I'm sorry that you are having difficulty installing Leopard. Leopard comes with full phone support, so if you are having issues with the installation or operation of the OS call Apple directly or better yet, get in touch with your local Apple store and a Mac Genius can easily assist you.
A few of the major issues that we have encountered at our Genius bar are:
1) Repairing permissions. Before installing Leopard it is CRUCIAL to repair any and all disk permissions through "Disk Utility" in Applications->Utilities. It is also important to do this whenever a major software update is released (in this case, if you opted to "Upgrade" or "Archive and Install" with Leopard, it's imperative do run this procedure). Simply open "Disk Utility", select "Macintosh HD" and then below there will be an option to "Repair Permissions". I recommend doing this before and after any installation or software upgrade.
2) Third party applications that "tweak" the Finder and GUI (especially Unsanity's applications) have been known to cause MAJOR issues with the Finder's functionality. Uninstalling the applications will not work as they alter contents packages of Tiger files that Leopard needs to find and either replace or alter during an installation/upgrade. I have had to clean install a PowerPC system that had traces of WindowShade from Unsanity as the Finder was irreparably destroyed and the "Beach ball of Death" wouldn't go away in the users' accounts.
3) When all else fails, back up, and then perform a clean install, then reload documents and applications manually. What people are failing to realize is Leopard is a completely RE-WRITTEN OS. 64-BIT is new for this particular little guy, so upgrading or adding to an existing OS that may have numerous alterations and third party applications that may have not been tested with Leopard is inevitable.
For the most part, 95-98% of Tiger to Leopard installations have run very well to my knowledge. I appreciate that a few of you have had difficulties or are unhappy, but blaming Apple and throwing your hands up isn't the solution. Try "Repair Permissions" under "Disk Utility", deleting any third party applications AND their preference files (.plist files for said application that are usually in the MacintoshHD--->Library--->Preferences or (UserAccount)--->Library--->Preferences) and getting a hold of an Apple rep for specific assistance. If that doesn't work, back up and perform a Clean Install.
Good luck to all.