If you want to download torrents on a Mac you can use some free software called Transmission. But transmission is not like Azureus where it will search for torrents for you, at least the older version I've got isn't. It's merely a torrent client that handles the upload/download for you. I have to use third party torrent sites to search torrents. They may well have incorporated a search engine into the latest version but I don't need it so I've never updated. Also, if you're going to be downloading torrents on a mac you'll probably need another free application called UnRarX which will unpack compressed Rar files. If you're downloading HD video you might also need VLC to play MKV files, or If you have a low spec mac then download Perian and use it in conjunction with QuickTime as it uses less processing power to play the files. There are many alternatives to the above, that's just how I'd do it.