Install any Linux distro directly from hard disk without burning any DVD
"The prerequisite of this trick is to have an operating system already installed on your computer. This is obvious because unless you are able to boot into your machine, you can't install anything; and we are not going to boot from the Linux disk because we aren't burning any. Here I'm going to focus on Microsoft Windows as the pre installed operating system.
"Almost all Linux installers uses two files to boot the computer: a Linux kernel, and an initial root file system containing a minimal set of directories that is mounted prior to when the real root file system is available. This initial root file system is also called Ram disk (initrd). We will use these two files to boot our PC. Now lets get to the actual procedure."