Save the articles together with the word you are using placeholders for. <img src="/ubbthreads/images/graemlins/winkwink.gif" alt="" />
"Take this %1 to the %2 and get a %3 as reward."
%1 = book, box, treasure
%2 = trader, guard, warrior
%3 = sword, axe, hammer
Now in German:
"Bringe dieses Buch/diese Kiste/diesen Schatz zum Händler/zur Händlerin/zum Wachmann/zur Wachfrau/zum Krieger/zur Kriegerin und du erhälst ein Schwert/eine Axt/einen Hammer als Belohnung."
Sure, you could store "dieses Buch" instead of "Buch". But what if you don't need "dieses Buch" but "jenes Buch" or "das Buch" or just "Buch"?
Believe me, it IS very difficult to deal with such things. And yeah, a few friends of mine who studied computer science keep telling me that the best idea would be to find an automated way of translating a game... with a tool or something. But if you think of how much the German players complain about poor translations, do you think they will be happy about a more or less automated localisation?