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There is no Nero on OSX....Well , OSX Bulit-in Disk Ulitly or Toast should able to burn iso out of the box , you should not have the problem

Control Click or Right click and select Open with and choose DiskUtility , then select the .iso , on the file list and hit Burn...and vola , it will burn as an ISO

Trust me , I have burnt a Windows 2003 ISO , and it works on a PC...I can even boot from it

Double click the ISO , thats it. OSX would mount it , just like a .dmg

or use Toast

If you have toast installed , make sure you lock the file [so it would be read only] and select Mount It !...vola , you got an emulated CD..Its much like DeamonTools for Windows !