I want to convert polygons into points using QGIS.
I know how it's done in ArcGIS Desktop.
How can I implement it using QGIS?
You can do the "Centroids" in QGIS using:
Vector > Geometry Tools > Centroids
If you want to decide on your own point spacing, you can use the Sextante Toolbox with SAGA functionality activated (you'll need to install SAGA - http://www.saga-gis.org/en/index.html - and specify the installation path in sextante).
Note: you have to make sure you install the right version of SAGA - I think its 2.0.8