So there's this pop singer... you may have heard of her? Madonna, she's called, and the word is that she's basically all image; she went through a put-your-hands-all-over-my-body phase, then she got spiritual, and then she started wearing cowboy hats. Between all the gossip columns and photo shoots, though, she's left an unmatched trail of devastatingly wonderful singles--roaring dance records, tender ballads, and a curious combination of the two that is her personal specialty ("Secret" and "Ray of Light"). How many artists' best-of-the-second-decade collections crowd out legitimate hits? ("American Pie," anyone? "This Used to Be My Playground"?) Unlike 1990's Immaculate Collection, GHV2 doesn't have any new material; "Don't Cry for Me, Argentina," from Evita, and the glorious '60s pastiche "Beautiful Stranger" are the only songs that haven't appeared on a Madonna album before. But it compresses her past 10 years worth of records into an hour of one peak after another.