I'm afraid I have to disagree with Ralf regarding all season tyres. We've had them fitted to two cars now, Michelin Cross-Climates on a Suzuki we had, and on my wife's 500C Nexen N Blue 4 Seasons. On both cars they reduced the noise compared to the OEM tyres - "economy" rated tyres generally have firm sidewalls which transmit more noise. All-season tyres use a more compliant compound.
We also found the Nexens improve the ride on the 500.
Finally, although the Nexens have yet to be tested in snow, the Michelins on the (2WD) Suzuki were fantastic when we had the "beast from the east" a couple of years ago. Highly recommended.