Mac OS X already comes with the Disk Utility app which you can use to burn ISO images into a CD/DVD. You don't have to buy or download a new app to just do that. The step-by-step procedure is shown below.
- From Finder, open the ISO image with Disk Utility (that's via "Open with" in the finder context menu).
- From the list in the sidebar, click on the ISO image.
- Hit the "Burn" button and insert a blank CD
It's that simple, no more apps to download. Credit is due to macworld forum for this but I won't link the post since there's a lot of chatter there that aren't necessary.