Saturn Corp. is breaking a yearlong campaign this week that will feature 5-minute spots. Rather than Saturn cars, the spots show the building of Kids' Kingdoms -- the Saturn dealers' project to refurbish playgrounds. Five cable networks will air most of the short infomercials in prime time: Comedy Central, f/X, E! Entertainment Television, Discovery Channel and Learning Channel. Hal Riney & Partners, San Francisco, created and placed the spots.