Here’s help for PC to Mac switchers who wish to create a MAC image that can be burned on a PC.
Mac Help – Convert and Burn Mac .dmg or .img to .iso Windows PC-Compatible Disk Image

Other details here may be helpful as well: Create an ISO image on Mac OS X using built-in Disk Utility App – CD and DVD Burning Software

And while we’re at it here’s a handy guide for burning to an external DVD burner from the MAC: Mac OS X iso img DVD Burn guide

One more pointer — this piece of software makes burning disks on the MAC a breeze: Burn