In QGIS 2.0 Dufour CRS-Settings are „hidden“ in a new menu (not anymore in „Settings“ like in 1.8).

• Menu „Project“ – „Project properties“
• You’ll find an entry „CRS“ ! Now you can choose your dedicated CRS and activate „on-the-fly“ transformation. Using „on-the-fly“ be aware of the correct transformation parameters for your CRS.
• The parameters for Austria (see Screenshot) are OK and there is no difference between using ArcGIS 10.x and QGIS 2.0