I analysed your images and this is what I see:
Coded Character Set : UTF8
Keywords : Luge, Rodeln, Sport, Welt Cup, Welt-Cup, Weltcup, Wintersport, World Cup, Worldcup
Caption-Abstract : in Igls, Österreich am 25.11.2012...Test Words: Österreich Köln Füße ändern
Image Description : in Igls, Österreich am 25.11.2012...Test Words: Österreich Köln Füße ändern
The text is therefore correct. However, the encoding of the IPTC is UTF-8, not the Latin-1 you wanted. My guess is (Kirk, please correct me if I'm wrong), that as soon as the encoding is UTF-8, it stays UTF-8; there's no way “back” (at least not with PM)
I noticed you used Photoshop CS4 to edit your images, my guess is that turned-on the UTF-8 encoding of the IPTC data (you wrote you hadn't). Quick testing with CS6 shows it converts the IPTC encoding to UTF-8 (I think when there are “special” characters present).
Please note that your database software is quite archaic and is in need of an update: IPTC (while still supported by PM) is the old standard. These days everyone standardises on the much more versatile xmp (which does not have your character encoding problem as it is always UTF-8). I can see this is no immediate solution to your problem, though