microsoft is providing a simple tool which will make a bootable usb key from whch you can install windows. simplifies a process that involved a lot of diskpart commands and some copying/extraction.
"The Windows 7 USB/DVD Download tool allows you to create a copy of your Windows 7 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 directly from the USB flash drive or DVD."