The short answer:
A 500MB Windows 7 ISO is almost certainly a stripped mod or a trap. For real-world use, stick to official ISOs or lightweight Linux distributions (like Puppy Linux or antiX) that are designed to be small, secure, and legal. windows 7 500mb iso
If you need Windows 7 for legacy hardware, use the official ISO and apply the and SHA-2 support updates manually after installation. The short answer: A 500MB Windows 7 ISO