Which software is used to compress a 3 GB file to a 9 MB rar file?

18 Mar 2010
18 Mar 2010 | |

Just today I downloaded Windows 7 final retail version from Rapidshare. It was just a 9 MB .rar file, but when I extracted it, it became exactly 3.49 GB. I even installed Windows 7 from it for dual boot with XP.

I know they used a compression software. But which software do they use for such conversion? Please answer me.