Ipod feature

I am looking to have a windows and mac version of software designed that will compress the hard drive of an IPod. For example, the user installs our software on their pc or mac and plugs their IPod in and our compression utility compresses the IPod's hard drive to allow for more space. (A 40Gig IPod is compressed to allow of 50Gig of space). We would like the software to have a mac interface design to it. Also, include costs for incorporating eSellerate.net SDK for software licensing.

Include pricing and timeframe.

--------------------------------------------------------------------------------
Here is something I want to ask about the project:

Someone told me this:
--------------------------------------------------------------------------------------
The music files uploaded to the ipod are already compressed, adding a compression scheme will only waste space and computation power. Compression would only be useful with arbitrary files, the ipod doesn't have much processing power and this un/compression would need to be done on the host computer.
--------------------------------------------------------------------------------------

I was under the assumption that even though the .acc (apple music files) were in a compressed format compressing the hard drive would allow you to put more of those compressed files on the iPod – am I wrong in that assumption..?

Also, can someone who is interested let me know what kind of compression ratios we can expect..

I want to add that communication and deadline is very important for this project.
So if someone can answer the above and is able to work with us, please reply!
I want to get this project done asap.