There are official links to obtain the ISOs. Useful when developing and creating virtual machines. Enjoy!
Windows 7 Home Premium x86 SP1 ISO
Windows 7 Home Premium x64 SP12
Windows 7 Professional x86 SP1 ISO
Windows 7 Professional x64 SP1 ISO
Windows 7 Ultimate x86 SP1 ISO
Windows 7 Ultimate x64 SP1 ISO
Creds: http://www.mytechguide.org/10042/windows-7-sp1-iso-download-official-digitalriver-links/