In many parts of the world, downloading 3–4 GB can take hours or even days. A 1.5 GB file is significantly more manageable.
Older USB drives (4 GB or less) may not hold a standard ISO after formatting (since usable space is often under 3.7 GB). A compressed ISO that extracts to a bootable USB solves this problem. Windows 7 Ultimate Iso Highly Compressed
A: No. You must decompress it back to a standard ISO first. Burning a .7z or .rar file to a DVD will not boot. In many parts of the world, downloading 3–4