Carboplatin and Pemetrexed in Recurrent Platinum Sensitive Ovarian Cancer

* Before patients receive any chemotherapy treatments they will be given three medications to prevent side effects from the chemotherapy drugs. These medications are vitamin B12, folic acid and dexamethasone. * Chemotherapy treatments will be given intravenously in the outpatient clinic. Pemetrexed will be given first and will take 10 minutes to infuse followed by carboplatin which will take 30-45 minutes to infuse. These treatments will be repeated once every three weeks for 6 cycles of chemotherapy (18 weeks). * Before each chemotherapy treatment the following tests and procedures will be performed: physical exam and medical history; evaluation of ability to undertake daily activities; and blood tests. * After every 2 cycles of chemotherapy (every 6 weeks) patients will have a CT or MRI scan to measure how well their cancer is responding to treatment. * The study treatment will last for 6 cycles of chemotherapy as long as the tumor does not grow and the patient isn't experiencing any severe side effects.