Windows 7 can be easily installed by windows bootable USB and no need to use the Optical drive for installation anymore. The windows bootable USB is free tool from Microsoft allows you to take a .ISO image and turn it into a bootable flash drive. windows bootable USB tool was created not only for netbook /laptops users, but this can be download for Windows 7 from Microsoft in lieu of ordering an installation DVD. Windows 7 windows bootable USB Tool can be downloadable to create a bootable flash and ISO file in quick fashion—just install it and follow the on-screen prompts.
Note that if you opt to use a flash drive, it must be 4GB or larger to hold all the files.
The ISO file contains all the Windows 7 installation files combined into a single uncompressed file. When you download the ISO file, you need to copy it to some medium in order to install Windows 7. This tool allows you to create a copy of the ISO file to a USB flash drive. To install Windows 7 from your bootable USB flash drive all you need to do is insert the USB flash drive into your USB port, run Setup.exe from the root folder on the drive.
Note: You cannot install Windows 7 from the ISO file until you copy it to a USB flash drive with the Windows 7 Bootable USB Download tool and install from there. Download the Windows 7 Bootable USB tool
The copy of the ISO file that the Windows 7 bootable USB Download tool creates is bootable. Bootable media allows you to install Windows 7 without having to first run an existing operating system on your machine. If you change the boot order of drives in your computer’s BIOS, you can run the Windows 7 installation directly from your bootable USB flash drive when you turn on your computer.
Check the documentation for your computer for information on how to change the BIOS boot order to USB port on computer.