the downloaded ISO files.
Use ISOBuster to read and extract files from the ISO image.
As usual, Yves gives some bad advice disguised as good advice.
Roxio or Nero - good! Those will convert the ISO to a usable CD, but
take care to select the Burn Image option. Don't just burn the ISO
image to the CDR.
ISOBuster - BAD. Just extracting the contents of an ISO to the Drive
won't usually produce a file set you can use for installing.
Sometimes (but not very frequently) this works, but it's better to use
the ISO the way it was intended to be used.