Disk Utility will burn disc images, but there's more to burning than that.
You can create "burn folders" in Finder, much like you can in Windows. You can also burn DVDs in iMovie, and music CDs in iTunes. If you're looking for a comprehensive application like Nero or Easy CD Creator on Windows, take a look at Toast.
But before you go buying Toast (which may be overkill for your needs), have a look at Burn.
Toast is awesome. It has the built in ability to convert your media, ie movies, and convert them, I cannot recall the proper format not, MPEG2 or 4 whatever. But I can take a flick and convert it so it's ready to be imported into my iPhone. It's like a DVD burning software plus DVDFab that I used to use in Windows.
