I. To determine the maximum tolerated dose (MTD) of vorinostat in patients with newly diagnosed glioblastoma multiforme (GBM) and gliosarcomas, who are also receiving concomitant radiation therapy (RT) and temozolomide (TMZ). (Phase I) II. To define the safety of vorinostat with RT and TMZ in this population. (Phase II) III. To determine the efficacy of vorinostat in combination with RT and TMZ followed by vorinostat in combination with TMZ in patients with newly-diagnosed GBM and gliosarcomas as measured by overall survival at 15 months (OS15). (Phase II)