The installation of Quantum Gis (QGis) was very simple, just run the setup.exe file and it works. There is also a good documentation for the installation (which is needed for Linux user). (http://qgis.org/releases/install.pdf)
The user guide is very helpful and the program is, with a little experience with GIS software, pretty easy. (http://qgis.org/releases/userguide.pdf)

Testing with shapefiles:
-    The program is slow, sometimes it takes about a minute until something is opened or displayed.
-    Points: It is possible to define different symbols for different expressions in one layer. There are only 5 different symbols (circle, square, square standing on the vertex, plus, x) visible in the properties drop down list, but there are some more available (they are shown as white square). These additional symbols have their own color and don’t appear in the chosen color. It will be possible to add new symbols in SVG format with the next windows release. The current Linux (Debian) version 0.7.4 already supports SVG symbols.
-    Lines: it is not possible to have lines with an outline. It is not possible to add new line types.
-    Polygons: it is possible to define different colors for different expressions in one layer. Except from 15 simple geometric patterns there are no other available.
-    After defining a projection (Amersfoort /RD new) the map frame turns completely white, clicking the button "to full extend" the program closes immediately without any warning. Disabling the checkbox "enable projection on the fly" solved that problem, now it is the right projection.
-    The File extension has to be added to the name to export. Even if the format is chosen correctly below. E.g. save an image as png without defining the extension after the name results to an unknown file. Rename this file to xyz.jpg leads to the question if the user wants to rename the file, because it is a png file.
-    The exported mapfile presents a very simple map. Layers are only defined with one color even though the map contains several colors in one layer for different expressions. The projection does not appear in the mapfile and specified scales for the layer are also missing.
-    As the mapfile is so bad it was not possible to test it in map builder without changing and adding too many things manually.


Testing with PostGIS tables:
-    very slow and the program crashed several times, when I tried to use the time waiting for a response by reading the documentation or writing this report, but even waiting without doing anything else causes no respond.
-    properties for points, lines and polygons of PostGIS tables are the same like shapefile properties
-    It is impossible to open the attribute table of large data. Then the program does not respond anymore.
-    Loading data works, but changing the style is impossible, the program hangs up.
-    Exporting as mapfile causes the same problems like exporting from shapefiles.

Conclusion QGis:
Quantum GIS (QGis) is a nice GIS program but in my opinion not suitable to create and edit mapfiles by now. The program is very slow and does not work properly with PostGIS data. The exported mapfile is very simple and needs a lot of amendments. The more complicate settings in the mapfile (different expressions in different colors in one layer and scale setting when the layer will be shown) can be done for the map in QGis but will not be exported.
Edit a mapfile manually takes some time, but using QGis takes about the same time with a worse result.