|"I did notice that the oph files that were downloaded did not include an .exe file could that be another reason?"|
The file that makes the disk bootable is usually an *.img file. You can't see it in Vista, or other operating systems, itself. E.g. all Microsoft OS CDs have an *.img file.
Look where you got the download from. There is often info there, or links to info, about how to make the disk properly so that it's bootable.
I have a free version of Nero that came with a Sony DVD burner drive. On other peoples computers I've worked on, they had a similar free Nero version that came with a LG DVD burner drive. All of those require that you use another third party prgram to extract an *.img file as well as follow a procedure in the burning program.
In some cases, the place you download the CD contents from may have an *.img file that you can download that will work fine.
The only bootable CDs I've made are "slipstreamed" XP CD-Rs that have the SP3 updates integrated into the contents of an original XP CD that did not have SP3 updates.