DON'T use a torrent. They're illegal.
Buy it through Steam. And plus, that way it installs by itself.
One note: to use Garry's Mod, you need to have another game that uses Valve's Source engine installed. (Portal/Portal 2 will do)
Without stories, we wouldn't be human beings at all. -- Philip Pullman // 09F911029D74E35BD84156C5635688C0