To run Windows 7 Ultimate SP1 (32-bit) effectively, your hardware should meet these minimum requirements: : 1 GHz or faster. RAM : At least 1 GB. Hard Disk Space : Minimum 16 GB for the 32-bit version.
: You still require a valid 25-digit product key to activate the software after installation.
Since official support has ended, the is the most reliable repository for "untouched" or original MSDN ISO images.