Appleworks: A cheap but effective version of Microsoft Office.
iTunes: Hands down, the most impressive computer mp3 player and interactive music application. (It may come with iTunes 3, not 4, though.)
iMovie: A simple video editor.
iPhoto: A simple and free photo editor with basic features.
Preview: A simple image viewer
Quicktime Player
A few other apps you mayfind useful, others for when you have free time.
You forgot Sherlock, that has to be the most useful piece of software in OS X. Well if you like in the USA. I'm in Canada and the directories are unfortunetly very limited.