"The Genius' 20 Greatest Hits." Ray Charles. Platinum. "The CD of JB." James Brown. Polydor. These essential collections, specially designed for the compact disc market, don't showcase every side of these extraordinarily influential artists (both just inducted into the Rock Hall of Fame), but the bargain packages offer a generous sample of their best-known pop and soul hits. CDs cost twice as much as conventional LPs and tapes, but that gap is offset here because you get almost twice as many songs as on a regular single-album "greatest hits" package. Both .