A typical Cheetah ISO (or CDR) is approximately 650-700 MB . The file name might be something like Mac OS X 10.0 (Cheetah).cdr . You will require all 4 CDs to install the full suite of applications (iTunes, iMovie, etc.).
Searching for a "Mac OS X 10.0 Cheetah ISO" reveals a common misunderstanding. The term "ISO" technically refers to an ISO 9660 file system, commonly used for Windows or Linux CDs. Mac OS X 10.0 was distributed on a hybrid CD-ROM using Apple's proprietary HFS+ (Hierarchical File System Plus) format. Mac Os X 10.0 Cheetah Iso Download