If you want to buy a dedicated product to burn stuff to disc with then Toast is probably the most popular option.
I personally don't use it, to burn a music CD I will use iTunes, to burn a photo cd Aperture/iPhoto etc. To burn files and folders straight to a disc you can just use finder and drag and drop away
When you say burn DVD files do you mean write DVD movie files to disc, or just burn DVDs in general?
The built-in program for OS X will work fine.
Anything else and I'd suggest Toast by Roxio
Built in program?
yep, Toast and Burn are probably the two best burning progs for OSX, although check out Disco! I like it for the awesome burning smoke effect when you burn a cd
With Disco we tried pushing the boundaries of interface, usability, and utter functional simplicity. Well, once you realize that Disco is emitting real time interactive smoke as you burn, we start redefining the boundaries. Want to push it out of the way? Blow into your microphone and the smoke will react accordingly. Or, go ahead and flick at it with your mouse. Remember, you'll need a recent mac to play with the full interactive smoke.
Aha, I wondered what burn folders were about when running candybar once, thanks.