This is becoming quite a heated argument so i'm going to stick my oar in at this point.
It's all very well to say Lucas created Star Wars out of nothing but the fact is Star Wars was, at one point, so close to the Hidden Fortress that Lucas had to look into acquiring the rights to it. In the end he didn't need to because; see next point.
Lucas, while he wrote the first draft employed a number of writers to to produce his screenplay and his novelisation not only for ANH but for ESB and ROTJ. It was these writers that solved alot of the issues that meant he almost had to licence Kurasowas film.
Lastly, Star Wars ANH is basically your average fairy tale set in space. I'm not knocking the movie, infact the Original Trilogy is magical but don't ask me for an opinion on the new stuff, you might not like my answer.
Anyone wanting a little more info on the creative process behind the Star Wars legend should check this book http://images.amazon.com/images/P/0006530818.01.LZZZZZZZ.jpg
It's really good and it gives alot of juicy information that you'll never get out of Lucas or his company.
As for Peter Jackson, while its agreed he's had source material to work from, the task was just as daunting as if he was making a movie from scratch. Not only did it require substantial editing so it could actually fit it into 3 movies, there was also the design work and as someone said before the special effects were created on the fly. While Yoda in AOTC is impressive, he's nowhere near as complex as Gollum.
Also, I don't know where some people are getting the idea that the world of LOTR is small in comparison to Star Wars. Tolkien spent most his LIFE creating that world and his son has continued to add to it. Anyone who's read the books would know that not only is there plenty of history pre LOTR but there's also quite a bit of information to tell you what happened AFTER. Add to that feat the creation of a Language and it becomes an even bigger accomplishment; to say that the 25 or so books of the EUSW is bigger in scope and concept is lunacy.
And one final point, Lucas doesn't consider any of the EU stuff canon. So in that sense, it might as well not exist.