Vouk is an interesting name, doing a serach on the Online Austrian telephone book returns many entries of the name in many parts of Austria.
Doing a search in www.infoseek.de
and restricting the search to Austria brings up (at least) 2 links to note!
One is for an accomplished Swimmer from Klagenfurt who recently won a Bronze medal in a Jumping competition in France.
And the other link is the following: For a head of one of the Slovenian Ethnic Groups in Carinthia.
You mentioned St.Jakob, so I presume you mean St.Jakob in Rosental, an area I too am researching. It was traditionally an area of many Slovene-Austrianshttp://www.derstandard.at/Textversion/19990910/166.htm
Keep us informed on your research!