Temozolomide Plus Peripheral Stem Cell Transplantation in Treating Children With Newly Diagnosed Malignant Glioma or Recurrent CNS or Other Solid Tumors

DISEASE CHARACTERISTICS: * Histologically confirmed newly diagnosed malignant glioma or recurrent malignant CNS tumor of any pathology OR * Histologically confirmed non-CNS tumor * Recurrent soft tissue sarcomas (e.g., rhabdomyosarcoma) * Recurrent or resistant neuroblastoma * Recurrent Wilm's tumor * Recurrent Ewing's sarcoma * Recurrent primitive neuroectodermal tumors * Recurrent nasopharyngeal carcinoma * Recurrent germ cell tumor * Expected cure rate less than 10% with standard therapy * Measurable and/or active disease * History of bone marrow tumor infiltration with or without mass lesions or isolated abnormal CSF cytology as only evidence of recurrent disease allowed if complete response was first achieved with primary conventional therapy PATIENT CHARACTERISTICS: Age: * 18 and under Performance status: * Karnofsky 70-100% OR * Lansky 70-100% Life expectancy: * Greater than 8 weeks Hematopoietic: * Reasonably cellular bone marrow (greater than 15% cellularity on biopsy) * Absolute neutrophil count greater than 1,000/mm\^3 * Platelet count greater than 75,000/mm\^3 Hepatic: * Bilirubin less than 2.0 mg/dL * SGPT less than 120 U/L Renal: * Creatinine less than 1.5 mg/dL Cardiovascular: * Systolic fraction or ejection fraction at least 80% predicted for age by echocardiogram Pulmonary: * CVC or DLCO at least 60% predicted for age OR clearance from pulmonologist Other: * Not pregnant or nursing * Negative pregnancy test * Fertile patient…