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