Windows 7 ISO from Official Website
Here is the list of Urls you can download different versions 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
http://msft-dnl.digitalrivercontent.net/msvista/pub/X15-65732/X15-65732.iso
Windows 7 Home Premium x64 ISO 64-bit
http://msft-dnl.digitalrivercontent.net/msvista/pub/X15-65733/X15-65733.iso
http://msft-dnl.digitalrivercontent.net/msvista/pub/X15-65804/X15-65804.iso
Windows 7 Professional x64 ISO 64-bit
http://msft-dnl.digitalrivercontent.net/msvista/pub/X15-65805/X15-65805.iso
Windows 7 Ultimate x86 ISO 32-bit
http://174.129.85.117/data/Windows7Ultimate32bit.iso
[UPDATE August 8th 2011] After nearly a year of the release of Windows 7 Service Pack 1, you can now download new Windows 7 ISO images that comes with the Service Pack 1 (SP1) pre-installed. That means you don’t need to download all the windows updates for a fresh new install, this will save you many hours after your fresh install of Windows 7. It is strongly recommended downloading the new ISOs that come with Service Pack 1 pre-installed. As usual, the links below are all from official Microsoft retailer website.
Windows 7 Home Premium Service Pack 1 x86 ISO 32-bit
http://msft.digitalrivercontent.net/win/X17-58996.iso
Windows 7 Home Premium Service Pack 1 x64 ISO 64-bit
http://msft.digitalrivercontent.net/win/X17-58997.iso
Windows 7 Professional Service Pack 1 x86 ISO 32-bit
http://msft.digitalrivercontent.net/win/X17-59183.iso
Windows 7 Professional Service Pack 1 x64 ISO 64-bit
http://msft.digitalrivercontent.net/win/X17-59186.iso
Windows 7 Ultimate Service Pack 1 x86 ISO 32-bit
http://msft.digitalrivercontent.net/win/X17-59463.iso
Windows 7 Ultimate Service Pack 1 x64 ISO 64-bit
http://msft.digitalrivercontent.net/win/X17-59465.iso
