SWIM recently downloaded final cut pro using bittorent, and the instructions within the torrent told him to unpack (which he did) and then install the .mpkg file. However, in the unpacked folder, there was no such file, just .nfo, .sfv, .r00 throught .r00 and a .rar file. Swim does not know how to unpack .rar files on a mac. What is a good (free) program for this?