Microsoft WorldWide Telescope

Microsoft WorldWide Telescope screenshots

A virtual telescope that lets you browse though the known universe
Solar System
Microsoft WorldWide Telescope 2.1 : Solar System

Alternative downloads

Alcyone Astronomical Tables
Alcyone Astronomical Tables provides various astronomical information.
MPL3D Solar System
This is an interactive 3D space simulation of the close universe in real time.
Planets of the Solar System
It is a comprehensive reference with illustrations.