This is more of an FYI than a hint. When installing iLife 09 from the DVD, I noticed that the install said that it was doing a Standard Install, so I clicked the Customize button. In the list of individual programs, I found that there's an additional 600MB+ of iDVD Extras that aren't installed by default.
These extras are the themes from the first five versions of iDVD; if you think you might want these extra themes, make sure you tick off the box on the Customize screen, otherwise you won't get them.
Mac OS X Hints
http://hints.macworld.com/article.php?story=20090210125503415