COOK pasta in large saucepan as directed on package, omitting salt.
MEANWHILE, cook sausage in deep large skillet on medium-high heat 10 to 12 min. or until done, stirring occasionally. Drain; return sausage to skillet. Add spinach and tomatoes; cook 2 min. or until spinach is wilted, stirring occasionally.
DRAIN pasta; return to pan. Add sausage mixture and cheeses; mix lightly.