It was just a few short years ago that the most viable way of obtaining Linux was to order a cdrom from an online store. Now, thanks to the introduction of broadband internet access and cd burners, you can simply log onto any of the sites below, download the latest ISO Image and burn it to a cdrom. It is perfectly legal, 100% free and totally convenient. Isn’t open source great? 
Once you’ve downloaded an ISO Image you can mount it as a loopback device. This will give you access to the files in the ISO without you having to burn it to a CDROM first. In order to do this you must have loopback compiled into your Linux Kernel. (Most newer distributions will have this enabled by default). For example if you wanted to mount filename.iso to /mnt/iso you would run the following command: mount -o loop -t iso9660 filename.iso /mnt/iso/
For more information, please visit: Linuxhelp.net