 This study is to compare the ulcer healing rate and ulcer bleeding at 12 weeks in patients with aspirin-associated PUD when they take PPI rabeprazole 20 mgday to treat their PUD and simultaneously take aspirin or clopidogrel for their cardiovascular CV prevention. Two hundred patients will be randomly assigned rabeprazole 20 mgday plus aspirin 100 mgday or rabeprazole 20 mgday plus clopidogrel 75 mgday for 12 weeks. The primary end point is treatment success ulcer healing rate. The secondary end point is incidence of ulcer bleeding within 12 weeks. 