Inclusion Criteria:  High risk Ewing's Sarcoma Family Tumors (ESFT) including Ewing's Sarcoma, Askin's tumor, peripheral PNET High risk desmoplastic small round cell tumors (DSRCT) Relapsed Wilm's tumor, diffuse anaplastic Wilm's tumor High risk brain tumors including PNET/Medulloblastomas/germinomas Relapsed germ cell tumors Metastatic or relapsed rhabdoid tumors Other relapsed/refractory pediatric embryonal tumors Less than 30 years of age Performance >= 50% Cancer Diagnosis verification and staging Disease Response and Recovery Adequate Organ Function (Renal, Liver, Cardiac)  Exclusion Criteria:  Uncontrolled Infection Pregnancy or Breastfeeding (For Females) Disease Progression Uncontrolled Intercurrent Illness HIV Positive Receiving other Investigational Agents Amifostine Allergy