uno + ethernet shield + sd card + download

I just had a wild idea but i don't know how to implement that, I am desperately waiting for some help.
I had a ARDUINO UNO REV3 and an ETHETNET SHIELD lying around, I want to make a device that can download content(i.e., videos, music, documents, etc,,.) from internet when it is connected to my router at work place (coz the network runs at cool speeds) and store it on the SD card, and I should be able to control it from my home. The problem is I don't know shit. I surfed the net but found nothing except for few examples. Please help me on this.

P.S. sorry for my BAD english

You need to:

What have already tried?

If you are not allowed to use your work PC to download the content and then copy it onto an SD card why do you think you are allowed to do this with an Arduino device and why do you think you will get away with it.

Interesting concept though - could you get away with this at a public internet service that had Internet ports you could access. I wonder if you could use this technology to connect to any other devices and maybe take control of them. With an arduino set up hiding in a little box people might not notice your devious game.

Cheers

Cateeazle NZ