How is this complicated? The first six champions of this Millenia were: MSU, Duke, Maryland, Syracuse, UConn, North Carolina. Louisville and Virgina later won as well as Villanova. So that's 6 current ACC schools and 2 current Big East schools. SEC also has two (Florida, UK) and Big XII has two (KU, Baylor). Big Ten has just that one in 2000 and the old Pac had zero.
Even if you want to consider just the last decade, it's 3 ACC schools and 2 Big East schools.
For fun facts, the Big Ten dominates the loser side of the NC game. Since 2000, Indiana, Michigan State, Ohio State, Michigan, Illinois and Wisconsin have all lost title games.