I managed to finally get the weather working on my powerPc by downloading the latest version 1.01 update.
Then I looked up the default code for Amsterdam which is listed as NLXX0002
Opened up Safari, went to yahoo weather and typed in Amsterdam, it brought up a webpage with Amsterdam-727232, I went to view->view source and searched for the code " NLXX0002", it found it there, so I copied the line before that.
Went back into Yahoo weather, typed in Melfort, SK it loaded the weather, went to view page source in Safari and searched for the same line code, it pulled up CAXX0706
But interesstingly at the beginning, when I added the first customized city, went backt othe Weather overview and into the settings of that city again, I saw the information from the next city in the list, means from one of the standard places. I had to leave Front Row and come back to be able to see the correct settings. this behaviour continued untill I had deleted all preset cities.
The same behaviour occures if a wrong city code was entered, and interestingly if a not working RSS feed is configured in the RSS plugin.