This randomized phase III trial is comparing two different combination chemotherapy regimens to see how well each works in treating patients with previously untreated rhabdomyosarcoma or sarcoma. Drugs used in chemotherapy, such as dactinomycin, cyclophosphamide, vincristine, and topotecan, use different ways to stop tumor cells from dividing so they stop growing or die. It is not yet known which combination chemotherapy regimen is more effective in treating rhabdomyosarcoma.