"UNetbootin allows for the installation of various Linux/BSD distributions to a partition or USB drive, so it's no different from a standard install, only it doesn't need a CD. It can create a dual-boot install, or replace the existing OS entirely.
* Microsoft Windows 2000/XP/Vista, or Linux, or a USB Drive. If you are having trouble with the Linux version, try the Windows version, it usually works better.
* A broadband internet connection to download the distribution packages (unless installing from pre-downloaded media, see below)
* Spare hard drive space to install the OS in (varies depending on distribution)
UNetbootin can install to your local hard disk or make a bootable liveUSB drive. It can also load floppy/hard disk images, or kernel/initrds, or (some) ISO (CD image) files, for installing other distributions. [...]
UNetbootin loads utilities or installs Linux/BSD to a partition or USB drive without a CD. It can use an existing disk image/kernel/initrd file, or download a supported distro or system utility (such as Ubuntu, Fedora, openSUSE, FreeBSD, PartedMagic, etc.)
UNetbootin uses a Windows or Linux-based installer to install a small modification to the bootloader (bootmgr and bcdedit on Vista, grldr and boot.ini for NT-based systems, grub.exe and config.sys for Win9x, grub on Linux, or syslinux when installing to a USB drive), uses the bootloader to boot the desired distribution's installer or to load the system utility, no CD required. After the distribution has been installed, or once done using the system utility, the modification to the bootloader is then undone."