This tutorial will show you how to install windows 7 or 8 really on any usb storage.

Step 1: Step 1: Download NT6.X_fast_installer

Link:

Step 2: Step 2: Extract and Run Installer As Administrator

Extract the rar file best to the root of HDD

Go to the folder and run installer.cmd as administrator

Before image 1 mount windows 7 or 8 iso file you can do it with daemon tools lite Link: http://www.daemon-tools.cc/eng/products/dtLite

Afther that follow image 2

Afther that follow image 3

Then type the letter of the partition where do you want to install windows
Boot partition=the same letter like in OS partition

Is [your drive] : a USB hard disk? (Y/N): you must type N it's important press ENTER

Then press ENTER and installing begins!

When is the installing completed

Then restart your computer and boot it from your flash drive

If you have installed windows 7 follow the installation steps

If you have installed windows 8 boot it. The window with error isn't error and don't press OK. Press Shift+F10 and type cd oobe press ENTER

and msoobe press enter and follow installation steps.

After that you can reboot and use windows on flash drive.