Is it possible to install an iso image of an OS onto a computer without needing to burn it to physical media such as blank Dvd etc?

u can do install from your HD from an iso image or u can do a network installation (only nfs supports graphical mode installation)

here is the link from RedHat on HD installaton: http://www.redhat.com/docs/manuals/e...d-install.html

here is the link from RedHat on network installation: http://www.redhat.com/docs/manuals/e...-installs.html

in the instruction for RedHat it may talk about copying from the CD but you may just download the ISO in the appropriate location.

You can boot the iso on a virtual machine which has been configured properly to hook onto one of you hard drive partitions (other creative methods are possible). I would suggest, however, that you NOT let the distro "auto-configure" your hardware until after you've booted on your real computer (obviously this will depend on what distro you use).

The precise method may need tweaking depending on how the distribution is "normally" installed from CD (e.g., sometimes, there is a minimal installation, followed by a reboot, followed by package selection and system configuration; sometimes there are more or fewer steps in a different order). You would probably want to copy the contents of the iso to a uniquely identifiable directory in the destination drive (for example, for package installation) which you will later remove.

One thing I've obviously left out is a bootloader (since I assume you already have one). Anyway, a bootloader can usually be installed from within the host OS (or at worst a boot to floppy).