Quantum GIS (QGIS)

QGIS

Quantum GIS (QGIS) is maybe the most user friendly Open Source Geographic Information System (GIS) which is curently available. It is suitable for beginners of GIS and advanced users who can write their own scripts or add modules written in Python. QGIS is licensed under the GNU General Public License and is an official project of the Open Source Geospatial Foundation (OSGeo). It runs on Linux, Unix, Mac OSX, Windows and Android and supports numerous vector, raster, and database formats and functionalities.

download source: http://www.qgis.org/

Hint:
In version 1.7.x and 1.8.x there is sometimes an “Entry-Point-Not-Found” error after installation. Here is how to fix this:

On OSGeo4W installing version:

1. Find path: C:\OSGeo4W\bin
2. Copy all files to location: C:\OSGeo4W\apps\qgis\bin\ 

On Standalone installing version

1. Find path: C:\programs (or program files) \Quantum GIS Wroclaw\bin\
2. Copy all files to:  C:\programs (or program files) \Quantum GIS Wroclaew\apps\qgis\bin\