 The purpose of this study is to determine if quetiapine fumarate extended-release quetiapine XR or SEROQUEL XR 150 to 300 mgday taken by itself is effective and safe in treating children or adolescents aged 10 to 17 with bipolar depression and if so, how it compares with placebo a non-active tablet, like a sugar pill, that looks like quetiapine. 