Also, activation issues: if the key is tied to hardware, using it on new hardware might not work and require reactivating, but since Microsoft is no longer supporting it, activation might be tricky. Maybe mention that.

Next, official sources: Microsoft's website? Wait, Microsoft removed the direct download link, but they do have a Windows 7 download page through the Media Creation Tool? Or maybe users have to use a product key to download through the Microsoft website. Also, maybe the Windows 7 USB/DVD Download Tool. But that tool is also deprecated. So unofficial sources might come into play here, but I have to be careful not to endorse or encourage piracy. Need to stress legal compliance.

For the all-in-one ISO, perhaps mention tools that combine both versions into one, but the user would need to choose the correct architecture during installation. So it's one ISO with options for both, which is helpful.

Also, for legal compliance, I must emphasize that downloading the ISO without a valid license is against Microsoft's policies. The paper should not promote piracy. Maybe suggest that the user has a valid license key from when they purchased the OS and use it to obtain a legal ISO.

Steps to create bootable USB or DVD. Using tools like Rufus, Windows USB/DVD Download Tool (if still available), or Disk Image Mounter on Windows. Also, for macOS/Linux users, maybe different tools.

Check if there are any updates or service packs. Windows 7 SP1 is the latest, so the ISO should preferably include that.