The easiest way to turn a USB flash drive into a bootable Windows 7 installer is by using the tool Microsoft offers, cunningly named the Windows 7 USB/DVD Download Tool. You are normally given this tool when you purchase from the online Microsoft Store. In order to follow this guide, you'll need a USB flash drive with at least 4GB of free space and a copy of the Windows 7 installation disc. This guide will show you two different ways to create a USB flash drive that works just like a Windows 7 DVD. Therefore, installing something like Windows 7 will work that much faster from a USB drive than from a DVD (and of course, is particularly useful for the PCs without an optical drive this isn't something we should just leave for the pirates to enjoy). Not only is it faster to copy data such as setup files from a USB drive, but during usage the access times are also significantly faster. There are reasons why you would, however, choose a USB device over a DVD disc, and bootable software is definitely one of them. USB drives tend to be higher in capacity than disc media, but since they are more expensive, they cannot (yet) really be used as a replacement. The USB flash drive has replaced the floppy disk drive as the best storage medium for transferring files, but it also has its uses as a replacement for CDs and DVDs.