Early apologies if you see this a little late - we've been married exactly one year now and the champagne might get in the way of uploading this issue everywhere. Time flies when you're having fun.
Turn Off Filename Extension Warning
In Leopard, Apple fixed an annoying aspect of working with the Finder in Tiger. Previously, if you changed a file's extension, the Finder prompted for confirmation. But since no one has ever accidentally changed a filename extension, Apple thankfully added an option to turn that warning off in the Leopard Finder's preferences. Choose Finder > Preferences, and in the Advanced screen, deselect Show Warning Before Changing an Extension.