Grooving its way out of your hi-fi like a late night television ad with a mind of its own comes Billboard Top Hits: 1975-1979. A generous of mix of R&B and AM pop-charting singles, the set boasts three Elton John songs, two tracks from KC & the Sunshine Band, the aching disco of Thelma Houston's "Don't Leave Me This Way," a few forgotten nuggets, and, of course, "Y.M.C.A." Because of their adherence to each year's charts, the five discs do have some continuity issues. But it's almost more fun that way. One second you're getting your groove on to Heatwave's "Boogie Nights," the next, you're screwing your face up to sing like Leo Sayer in "You Make Me Feel Like Dancing"." Rhino's Have a Nice Day and Disco Years series are more detailed in both hits and rarities. However, Billboard Top Hits benefits from its own brevity, and is as easy to enjoy than an old episode of Happy Days.