There are many ways you can obtain Windows 7. But

perhaps the easiest and fastest way to get Windows 7 iso image file is from the official HTTP server. That is you can download the iso image file from digital river and amazon

Here is the URLs you can obtain different version of Windows 7 (note: do not have Windows Enterprise, as it is exactly the same as Windows Ultimate but under different License Volume agreement, for average consumers there are only 3 version of Windows 7 available that is Ultimate, Professional, and Home Premium)

Windows 7 Home Premium x86 ISO 32-bit : Download Now

Windows 7 Home Premium x64 ISO 64-bit : Download Now

Windows 7 Professional x86 ISO 32-bit : Download Now

Windows 7 Professional x64 ISO 64-bit : Download Now 

World.4.Free brought to you by Alif Azhar