Oh, I don't know... there's just the first LOTR movie, the second LOTR movie, and the third LOTR movie as far as I'm concerned. Just as I can't be bothered to name the HP movie with its full name every time - it's still the Harry Potter movie for me, even though there's (with any luck) six more of them on the way.
Just as Star Wars is Star Wars, a lot more often than you see the individual titles mentioned - and if you do see the individual titles mentioned, it's usually with Star Wars attached to it (unless probably in SW-dedicated sites).
So it's the same with LOTR. And even for me, LOTR has always meant Lord of the Rings, and still does, after Rangers as well, even though the English abbreviations were never part of my social mythology or whatever you want to call them. /ubbthreads/images/icons/grin.gif