I was looking for a away to burn an ISO image the other day but instead of just getting some new software I thought I had better check if that Mac has this in already. If you are an old Mac user this might sounds stupid, but there is loads this machines can do outta the box and it seems every day im still learning. And on this learning curve i found out this burning ISO's is just another utility! The Disk Utility!>br? Its actuall simple
Insert your blank disc.
Start Disk Utility from Applications>Utilities.
From the File menu choose "Open Disk Image" and select the ISO.
In the list of volumes click on and higlight your ISO.
Then just click on the Burn button and follow the instructions. Thats it!