Often it is not possible to install the OS (Windows 7) from DVD. Sometimes devices dont have a dvd drive or you have only the ISO dowloaded from the Microsoft Download store. With USB installation you can save time but you need a USB stick with at least 4
<ul>
<li> you need at least a 4GB USB STICK</li>
<li> a original Windows 7 DVD or an ISO image, with another tool you can also create an ISO image</li>
<li>you pc or notebook must support booting from an USB device, you can check and change this settings in the BIOS otherwise you have to look into the namual</li>
</ul>