Microsoft has a tool which allows you to create a bootable* USB drive (or DVD, but dual-layer discs are not supported) for installing a copy of Windows. The tool is called: Windows USB/DVD Download Tool
The Windows USB/DVD Download tool allows you to create a copy of your Windows 7/8 ISO file on a USB flash drive or a DVD. To create a bootable DVD or USB flash drive, download the ISO file and then run the Windows 7 USB/DVD Download tool. Once this is done, you can install Windows 7 or Windows 8 directly from the USB flash drive or DVD.