Windows 7 is available online and has an instant download of an .iso image.
An ISO image is a mirror image of the DVD but it needs to be made bootable so you can start up the installation.
The first step is to download the ISO image to a place where you can remember it.? I normally download it straight to my desktop so it is easy to find.
Next, download a tool from Microsoft here called ISO Tool which will help you create a Windows 7 boot disk.? The software will install itself and ask you to input the path of where to find the ISO image (in this case, the file on the desktop) and then to insert a blank DVD or an empty USB drive.
The ISO image will be unpacked and burned onto a disk along with other files which make it look like a bootable disk.
Not only is this an easy way to make a burnable disk, it takes care of actually burning the ISO as well without downloading any bloatware software!