This is an old revision of the document!
Windows 7 is officially unsupported by Microsoft. Use at your own risk. That said, Microsoft Security Essentials still works, as well as PC Matic, which i haven't used, but has a lot of positive reviews.
Microsoft no longer officially offers any public sources for Windows 7 ISOs, but these links still work as of May 2022:
Unofficial downloads of Enterprise as of May 2022:
Additional ISOs are listed here.
There are some important update packages that may be required to get a new installation to a workable state (including the ability to find and download updates):
This update has two prereq packages, install these three packages in order: