If you want to install a new system to your harddisk,
You need write a install disc, it is a little bit waste.
Use external device … you need to backup the data in this external device,
format the external device, build the image to the external device …
However, if you don’t have these devices, how could you install a new system ?


Open Terminal and type

sudo gedit "/etc/grub.d/40_custom"

Add some menuentry

menuentry "Entry Name" {

    loopback loop isofile

    linux (loop)/casper/vmlinuz iso-scan/filename=isofile root=/ boot=casper quiet splash noprompt

    initrd (loop)/casper/initrd.lz

}

Save then back to the Terminal and type

sudo update-grub

Then reboot your computer

In GRUB2 menu, it shows the menuentry of ISOs

Select the specific menuentry to boot and install the system with that ISO file
(Temporarily, Ubuntu 9.10+ are tested and confirmed to be feasible)

Ubuntu 9.10

Ubuntu 10.04

Ubuntu 10.10

Ubuntu 11.04

BURG can also be set