http://www.disc-tools.com/download/daemon
Download, install, reboot when prompted to.

http://www.utorrent.com/
Download, and install, this is the program that handles
torrent downloads

http://thepiratebay.se/torrent/4443984/Diablo_2___Diablo_2__Lord_Of_Destruction
Download this, you only need the files that end in .ISO

when you're done downloading them, right click the demon tools icon in the taskbar
(the small icons in the lower right corner), select virtual devices -> select one of the devices 
and then -> mount - and select the iso files(start out with play).

now you have the files to install d2 on your hdd, so if you need to reinstall you can back them
up without having to download it again etc.
enjoy the best way of installing D2 and enjoy your first step into the world of software piracy