Scoring for film is radically different from composing for concert...and while John Williams music is absolutely fabulous for what it is, it is also extremely unimpressive in many cases....too much similarity between his themes is the most common complaint. This is not to say I do not admire him, the man is one hell of a tunesmith, and his ability to play the subtext of a scene is outstanding, but he's incomparable to Ligeti in terms of their respective contributions to modern compositional techniques. Regardless, you are quite correct in your assertion that Williams will be immortalized as a composer (he in fact, already is), film scoring is the only major compositional art form where you get to be famous before you're dead...lol
Film scoring is a very interesting work in itself, and the current people who are on top (Hans Zimmer, Danny Elfman, John Williams, etc...) are extremely good at their jobs. I just met Hans on Friday at the first Film Composers expo in Hollywood, he's absolutely hilarious.
I really want to hear Alex North's (I think it was North, I could be remembering it wrong) original score for 2001...North was king of the film composers for quite awhile at one point.
I do have to say that I like the irony in you thinking the Ligeti may have been Holst, while you praise Williams...I'm sure you are aware of this, but for people who don't know, much of the thematic content from star wars is liberally borrowed from/inspired by Holst's Planets Suite. Especially in the way the orchestration is arranged.
