If you are found to be eligible to take part in this study, you will be randomly assigned (as in the toss of a coin) to one of two treatment groups. Participants in one group will receive 5-aza and VPA. Participants in the other group will receive ara-C alone. At first, there will be an equal chance of being assigned to either group. As the study goes along, however, the chance of being assigned to the treatment that has worked best so far will increase.