Are the people in that picture still alive? If no, then we can't find a free substitute and provided it satisfies fair use conditions, I'd say you can use it.
Cheers!
Λuα (Operibus anteire) 15:15, 3 July 2009 (UTC)Reply
BTW, in the US, any work published before 1923 is in the public domain so you might want to check when the picture was taken exactly.
Cheers!
Λuα (Operibus anteire) 15:22, 3 July 2009 (UTC)Reply