the trial and the full game are the same thing btw
the trial just lets you set up a free 12 day WoW blizzard account
(I hope this isn't rule breaking territory here, I'm not telling him how, just what)
make sure you don't get a WotLK Torrent at it won't work on M-E
It must be 2.4.3 TBC to login to the server.
I know that I got mine through a friend who I believe got it through a torrent, which by the way, isn't illegal I don't think as Blizzard makes all their clients/updates freely available, it's the subscription they make their money off, not the game.
I just checked and their is a torrent for 2.4.3 on another server (ITRWoW) but you can modify the realmlist to point to any server you like