This post explains how to compress files to a great extent using KGB Archiver. You can compress files of size say 400mb to around 1MB using KGB Archiver.
KGB Archiver is a really good piece of software .It is open source software, which can be downloaded from sourceforge.net. (Sourceforge.net is thee home for a lot of open source utilities.)
It can be used to compress files either as a .ZIP file or as a .KGB file .It offers Minimal,
Very weak, weak, normal, Medium, Above medium, Good, Very good, extreme, maximum rates of compression.
It is recommended that you have at least 256mb of RAM. It can compress file of size of say 400mb, to around 1MB, using extreme compression. However it takes a lot of time to compress them .Some require even as high as 15 hours .But it is a really good utility for compressing.
Run KGB Archiver and select the compress files Radio button and click next.
In the Archive Text Box, give the destination file name with the directory.
The archive format can be either KGB or zip. Select the compression Level and then ad the files to be compressed and that is it. Just give next and watch your file get compressed to a great extent.