Pregnant or lactating females; Known history of active CNS disease; Uncontrolled ascites; Concurrent anti-cancer therapy; Gastric carcinoid, epidermoid, sarcomas, or squamous cell carcinoma; Prior palliative chemotherapy for the treatment of gastric cancer; Prior treatment with oxaliplatin < 12 months; Malabsorption syndrome or uncontrolled inflammatory gastrointestinal disease; Known history of uncontrolled or symptomatic angina, arrhythmias, or congestive heart failure; Pre-existing grade = 2 motor or sensory neuropathy; Uncontrolled infection; Concurrent disease or condition that would make the subject inappropriate for study participation or any serious medical condition that would interfere with the subject''s safety; Active hepatic or biliary disease; History of other malignancy except if disease-free for 5 years, a history of completely resected non-melanoma skin cancer, or a successfully treated in situ carcinoma; Unresolved or unstable serious toxicity from prior administration of another investigational drug and/or prior cancer treatment; Dementia, altered mental status, or any psychiatric condition that would prohibit the understanding or rendering of informed consent; Known history of DPD deficiency; Known immediate or delayed hypersensitivity reaction or idiosyncrasy to drugs chemically related to lapatinib, capecitabine, fluorouracil, platins or their excipients; Use of any investigational drug within 30 days prior randomization; Use of concurrent prohibited medications that would interact with study medications