Piano and harp ?
If you really mean "stringed" instruments as opposed to "string" instruments in an orchestral setting, then a piano and a harp qualify as non-bowed stringed instruments.<br />
Otherwise a classical guitar, and a lute (such as played in a Vivaldi Lute Concerto in a baroque orchestra), I suppose could be a non-bowed string instrument.
Actually, I sang for ten seasons with the Chicago Symphony Orchestra's Chorus, during the Solti and Giulini years.
Alex...is that you?