Working with ISO images is a PITA! Typically, I download ISOMagic or ISOBuster and extract the image to my hard drive. However, apparently, this functionality is no longer accessible with the free download. ;-(
I then discovered "Virtual CD-ROM Control Panel for Windows XP". Works under Win2K3 as well. The interface is clunky and I needed to start the "IMAPI CD-Burning COM Service" service but it provided exactly what I needed. I'm surprised this isn't just built into the OS...?