PATIENT CHARACTERISTICS: Age: Any age (5 to 55 to be eligible for randomization) Performance status: Karnofsky (or Lansky) 70-100% Life expectancy: Greater than 8 weeks Hematopoietic: See Disease Characteristics Hepatic: Bilirubin less than 1.5 mg/dl SGOT no greater than 3 times upper limit of normal (ULN) (both parameters stable for at least 4 weeks prior to transplantation) Renal: Creatinine less than 2 times ULN and stable for at least 4 weeks prior to transplantation OR Creatinine clearance at least 70 mL/min Cardiovascular: Fractional shortening greater than 28% on echocardiogram (23-28% if FS increases as a response to stress on supine bicycle ergometer) LVEF at least 50% on echocardiogram or MUGA Other: In good clinical condition at time of transplantation with no medical problems that would significantly increase the risk of the procedure No infection at time of transplantation Not pregnant or nursing