I would like to open files from an old ArcView 3.x project with Quantum GIS to work with the data. But this project data is saved as an APR-file, which I can not open with Quantum GIS. Is there any possibility to convert the data (for example to QGS files) to work with it?
There isn't a direct way to open .apr files in QGIS - but there is an extension for ArcView 3.x which lets you export views from ArcView to QGIS project files:
I've not used it - and notice the last update is over 3 years ago - but hopefully even if it writes an older style of .qgs file it will still be compatible! The QGIS export is also listed as 'experimental', which doesn't look encouraging.