You are right - previously, I've tested the selects using isql and when it returned no value for the NVARCHAR column, I though it has the problem as well. But it turns out that isql has problems getting any data from my table, but when I make a simple test table with unicode data, isql is able to return it correctly. So I keep on investigating. Your link didn't help, though, even forcing the type of the concerned column has no effect.
-- Micha