All patients in this trial will receive either the investigational drug or capecitabine, a chemotherapy drug that is already approved to treat your disease. These drugs prevent tumor cells from dividing, so they may stop growing or die. The investigational drug in this clinical trial is a chemotherapy drug given through the vein once every three weeks. Patients who receive capecitabine will receive this drug by mouth for 14 days, every 21 days.