NASA World Wind

http://worldwind.arc.nasa.gov/features.html

Official program from NASA for geographical info of the globe. Havent try it but it looks cool.

System Requirements

Windows 2000, XP Home, or XP Professional

Intel Pentium 3, 1 GHz, or AMD Athlon or higher

256 MB of RAM

3D Graphics Card
- nVidia GeForce 2 Ultra
- ATI Radeon 7500
- Intel Extreme Graphics 2

DSL / Cable connection or faster

2 GB of disk space

And here's afew screenshots I taken.