Why would you want to pay for software that is already covered as a standard part of all Linux distros?
In short, you can use an ISO file of a DATA CD and read it as a normal CD... but faster
At it's simplest you could do this (as the user
root):
mount filename.iso -o loop /mnt/cdrom
This will
mount the ISO file in the same place as your normal CDs, so you just need to browse to
/mnt/cdrom to access it.
A word of warning, though. If you intend on doing this with many ISO files one after the other, when you
umount it you should use the command like this:
umount -d /mnt/cdrom
This frees up the
/dev/loopX device which enables you to mount files as a
loopback device so you are free to mount another one, and then free it up and then mount another one, etc, etc.
I hope this helps.