In ArcGIS I used to create DEMs from contours with ease. However, we recently opted to stop using ArcGIS (for various reasons), and switching to QGIS.
The reason I use contour data is it is all that is available to me from our surveyor general (20m contour lines).
How can I convert them into DEMs?
There is no step by step GUI tut for GRASS on the matter, GDAL only uses point data, and IDW Interpolation does not produce a good quality DEM either.