Its funny because last year at Christchurch on the stray, they sang a hymn on remembrance sunday....and the tune was the German National Anthem
whilst I felt uncomfortable with that...it must be said that for example...this piece which is directly based on the same tune, used for a prelude wouldnt bother me at all
http://www.youtube.com/watch?v=HfmFpycqOKI
I believe that classical music, and organ music is alright in a church, most organ music, even used for some films, is far older, and written to be played as a prelude or postlude to the services...So I see nothing wrong with using the starwars theame as a bit of music to enter or leave by...Just like I would have no problem with this famous little gem
http://www.youtube.com/watch?v=ho9rZjlsyYY 
absolutely written for such a purpose!
Personally...I dont think secular songs have any place in worship...I dont even particularly think christian rock or grapevine type music really should be in an actual service.
I really perfer hymns, reasonable songs, and organ/classical music.