You know you're in the presence of a good new evening soap opera when one character remarks with abject dismay, ''I think everything's about to go as wrong as it can.'' So it goes with Winnetka Road, a promising light drama from the Aaron Spelling factory about the inhabitants of a midwestern town. In the pilot, written by John Byrum (Middle Ages), the subplots are rolled out with brisk efficiency. There's the middle-aged heel (Ed Begley, Jr.) who has left his wife (Catherine Hicks) and two kids for a nubile aerobics instructor (Jayne Lynn Frazer), only to find out that this new girlfriend is married. There's the Hollywood actress (Paige Turco) who returns to her hometown and rekindles an old romance with a local cop (Josh Brolin, the thickest slab of beef in prime time). Somewhere along the line, Meg Tilly puts on Kabuki make-up and startles the unemployed stockbroker (Kurt Deutch) who's just rented the apartment above her garage. I won't even go into the blind priest played by Eddie Bracken yes, Eddie Bracken.
So far, the stand-outs have been Hicks' wry-yet-spunky wronged wife and Tilly's sensuous eccentric. The only thing missing from Winnetka Road is an obvious villain-and, as you'd think Spelling would have learned from Melrose Place, you need an obvious villain in a show like this. B