WinToUSB is a free software that allows you to install and run Windows operating system on a USB hard drive or USB flash drive, using an ISO image or CD/DVD drive as the source of installation. WinToUSB also support creating bootable WinPE USB drive, it can help you to transfer the contents of WinPE to the USB drive and make the drive bootable. Additionally, WinToUSB can be booted on multiple computers. On the first connection, it automatically detects the system hardware, then downloads and installs the required drivers. So the next time it is connected to the same PC, it will instantly identify the proper tools. Because not all software supports running on such an operating system, it is advisable that they be tested initially, preventing you from encountering difficulties later on, when you might depend on that certain utility.