Thanks to your great input, I now have a perfectly running installation of Drupal.

However, just one quick question:

What would be the safe file permissions for a secure Drupal-installation?

I have chown-ed all the files/folder within the drupal folder to root.nobody (my Apache server runs as user "nobody"), but am quite unsure about a set of secure file/folder permissions. So far I've allowed read+write+execute to owner+group and everything works OK, but I would be thankful if anyone more experienced supplies some competent advice on this topic.

Cheers!!!