This month's Arts & Entertainment Preview is sponsored by Chrysler Corporation's Jeep and Eagle division, also a sponsor of programming on The Discovery Channel. Watch for The Know Zone (May 2 at 9:30 P.M.) and Wild Discovery (May 10 at 8:00 P.M.).Correct entries for the Arts & Entertainment Challenge will be eligible for a grand prize--I Got Rhythm: The Music of George Gershwin, the four-CD boxed set of Smithsonian recordings reviewed in our December issue.