how to download backtrack 5 iso to Virtial Box

Hi to all, I am new to this forum and would like to see if you can assist me with some help. I am going to school and we were able to download Oracle VirtualBox for class, I have Linux and would like to install Backtrack 5 if possible. Everytime I try to download Backtract it say it would take around 9hours to download and then fails. I have tried this on two different laptop via a wireless connection. Does anyone know a better way to download the iso so I can install it via virtialbox?

Thanks in advance..........

Anthony