I wish to install Windows 8 on my laptop. Currently, I have Windows 7 and Ubuntu 12.10 (Quantal Quetzal) available when I boot my computer up. Is there a way for me to install Windows 8 using a USB flash drive (16 GB) as opposed to a disc and in addition to Windows 7 as well as Ubuntu, at the very least keeping Ubuntu?
Next use the Windows 7 USB/DVD download tool (also available here, works fine with Win8) to transfer Windows setup to your USB stick from the ISO (if you have a DVD, you can create an ISO using something like ImgBurn). Alternately you can create the Windows setup USB directly from the DVD using WinToFlash, Rufus, WiNToBootic or similar tools. Boot from the USB and install Win8 into the empty partition created for it.
Finally you'll need to restore Ubuntu's Grub 2 boot loader (which would have been overwritten by Win8's graphical boot loader, which obviously can only recognise Win7 and not Ubuntu). This can be accomplished easily enough by running Boot Repair. Once this is done you'll be able to boot into any of the 3 OSes.