1. Download and Install Windows 7 USB DVD Download Tool Program by CLICKING HERE
2. Start the Windows 7 USB DVD Download Tool program. You should be able to find the shortcut on the Desktop, as well as in your Start menu or on your Start screen, depending on which version of Windows you installed the program on.
3. Click Browse on the Step 1 of 4: Choose ISO file screen. Then click Next
Note: If you don't have ISO image of your windows Then Learn How to Create ISO Image file of Windows by Clicking Here
4. Choose USB device on the Step 2 of 4: Choose media type screen.
5. On the Step 3 of 4: Insert USB device screen, choose from the drop-down box the flash drive or USB-connected external hard drive you want to put the Windows 8 setup files onto and then touch or click Begin copying.
6. On Step 4 of 4: Creating bootable USB device, just wait for the Windows 7 USB DVD Download Tool to prepare the drive and copy the Windows 8 installation files to it.
The first Status you see will be Formatting, which will take anywhere from a few to several seconds, depending on how large the USB drive is that you're using. Next will be Copying files which could take anywhere from 15 to 30 minutes, possibly longer, depending on which Windows 8 ISO file you're working from, as well as on how fast your flash drive, USB connection, and computer is.
7. Assuming everything went as planned, the next screen should say Bootable USB device created successfully with a Status that says Backup completed.
You can now close the Windows 7 USB DVD Download Tool program window. The flash drive, or other external USB drive you're using, now has the necessary files on it to install Windows 8 and is also properly configured to be booted from.
8. Boot from the USB device that you just created to start the Windows 8 install process.
Windows XP SP2, Windows Vista, or Windows 7 (32-bit or 64-bit)
Pentium 233-megahertz (MHz) processor or faster (300 MHz is recommended)
50MB of free space on your hard drive
DVD-R drive or 4GB removable USB flash drive
FOR WINDOWS XP USERS
The following applications must be installed prior to installing the tool:
Microsoft .NET Framework 2.0 must be installed. It can be downloaded here.
Microsoft Image Mastering API v2 must be installed. It can be downloaded here.