Coincedentally, I just happened to be surfing through youtube last night and I stumbled upon the Charlie Rose interview with GL and watched the whole thing. Here is the Charlie Rose interview with George Lucas from 9-9-04:

http://www.youtube.com/watch?v=Ep5oBO70xxU

I don't recall Lucas stating that qoute exactly as CO put above but he does mention that he needed more money to make the films he wanted on his own and the prequels were an opportunity to help him gain that finacial ability. I thought the interview was good, but Charlie drags out questions too long and doesn't keep much structure. He's not one of my favorite interviewers. GL seems like a smart guy, which makes me think maybe he has multiple personalities. One minuet he's smart and the next minuet he wants to put Jar Jar in every scene of Star Wars. I think one of you got it right. He's not really interested in the story of star wars but rather the process of playing with filmaking technology.