To determine whether tariquidar + combined first-line chemotherapy of paclitaxel/carboplatin in patients with Stage IIIb/IV NSCLC will, with an acceptable safety profile, significantly improve overall survival compared with placebo + paclitaxel/carboplatin. To compare the effects of tariquidar/paclitaxel/carboplatin with placebo/paclitaxel/carboplatin on tumor response, time to disease progression, performance status, symptom progression, and quality of life in patients with Stage IIIb/IV NSCLC.