Combine first 4 ingredients and 1 teaspoon pepper in a shallow dish or heavy-duty zip-top plastic bag. Add chicken; cover or seal, and chill 2 hours, turning occasionally.
Cook orzo in 2 cans chicken broth according to package directions; drain and set aside.
Remove chicken from marinade, discarding marinade.
Brown chicken in a large nonstick skillet coated with vegetable cooking spray over high heat 3 minutes on each side or until done. Remove from skillet; keep warm.
Sauté onion, garlic, and celery, in skillet coated with cooking spray until tender. Add remaining 1 can chicken broth and wine; cook, stirring often, 5 minutes or until liquid is reduced to 1/2 cup. Stir in orzo, Parmesan cheese, 3 tablespoons chopped sage, and remaining 1/2 teaspoon pepper; cook, stirring often, just until thoroughly heated. Serve immediately with chicken. Garnish, if desired.