This study will compare the effectiveness of craniotomy to that of stereotactic surgery (SRS) for the treatment of metastatic brain tumors - tumors that first develop elsewhere in the body and then travel to the brain. Craniotomy is surgical removal of the tumors through an operation. SRS consists of highly focused radiation doses to the tumors. Neither treatment is experimental and both have shown benefits to patients with metastatic brain tumors. This study will determine whether one treatment is superior to the other in prolonging patient survival.