Some computers might now have a working DVD drive and in such cases you can use a USB pen drive to install Windows 7 on it. To do this first connect the USB drive to your computer. Now go to the command prompt and run the 'diskpart' command to find the details of the hard drive. Use the 'List Disk' command to list all the drives on you computer. You can also find the USB drive in the list. Now use the Select disk command to select the disk. Perform a clean command of the disk. Next create a primary partition on the drive and select the partition. Now format the drive and this makes it ready to use it as a boot drive. Watch the rest of the video to know how to install Windows from it. This video shows how to install Windows 7 from a USB drive.