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
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
Step 3: Step 3: Follow the Pictures
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!
Step 4: Step 4: Completing the Installation
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.