It's actually from the same track I used in the Naboo Morning scene. It's from the '97 RotJ soundtrack, full name being "Brother and Sister - Father and Son - The Fleet Enters Hyperspace". The music I used for the Dooku Meeting scene starts about 3 mins into the track. There was no real deep thought behind using it though, as it was with "Brother and Sister". I just thought it worked really good with that scene. Though I did manage to time the various parts pretty good with what goes on. For example the Imperial theme playing as Padme talks about how much she and the Republic knows about Dooku's plans.

I did the same thing in the scene on Kamino where we first get to see the Clone Troopers marching and grouping. I changed the Droid Invasion theme (why was that even there?) to the Imperial march, making the March sort of a theme for the republic. This is to tie it in better with the OT, so that when people watch the films in 'correct' order I-VI and hear the march again in Ep V they are reminded of who these guys were and where they came from.