Operating system installers use two primary standard formats: (Windows Imaging Format) and ESD (Electronic Software Download).
Unofficial ISOs are frequently embedded with malware, trojans, or spyware . Because the OS is the foundation of your computer, a compromised version can steal passwords or enlist your PC into a botnet before you even install an antivirus. Windows 7 all versions highly compressed
If hardware resources are low, consider a lightweight Linux distribution instead of a potentially dangerous "highly compressed" Windows image. Windows 7 all versions highly compressed