 RATIONALE: Drugs used in chemotherapy, such as gemcitabine and capecitabine, work in different ways to stop the growth of tumor cells, either by killing the cells or by stopping them from dividing. Radiation therapy uses high-energy x-rays to kill tumor cells. Giving radiation therapy that uses a 3-dimensional image of the tumor to help focus thin beams of radiation directly on the tumor, and giving radiation therapy in higher doses over a shorter period of time, may kill more tumor cells and have fewer side effects. It is not yet known which regimen of chemotherapy given together with radiation therapy is more effective in treating pancreatic cancer. 