 For Cycle 2, methotrexate will be given by vein over 2 hours on Day 1 and over 22 hours on day 1. Cytarabine will be given by vein twice a day on Days 2 and 3. Each dose will take about 2 hours to give. Other drugs will be given before, during, and after treatment to help decrease the risk of developing side effects. These drugs may be given by mouth or by injection. 