What you need is a life style change, not a diet... A personal trainer/nutritionist would be ideal. The key is to get to the point of eating small meals/healthy snacks every 3 hours approx. and getting the proper balance of nutrition. After about a week your metabolism should start burning fat and stomache will shrink and you will get full faster. The hardest part is the mental lifestyle change. Most important is you have to do it for yourself, not for any other reason. This way you will stick with it.
As far as cardio/excersize, start small. Running could possibly cause more harm than good right now, for both heart and knees. Maybe start on a recumbant bike and light weight low rep workouts just to burn calories. Once you lose a good amount of weight you can start to pick up the workout.
Remember when you are overweight your heart is enlarged and has to work harder to pump blood and oxygen to your body. As you lose weight and your body falls into Ketosis, you will burn more and you heart will get smaller and will not have to work as hard. Warning: If there is an abrupt regression back to an unhealthy state the person could be at risk from heart complications, due to the sudden re-enlargement of the heart.
Once you start eating right you will see and feel results with in weeks.I have seen people lose 40lbs just by cutting out soda and drinking more water. Start by cutting out soda, fast foods, processed sugar, and salt/sodium. I would look into things like menshealth.com "belly off" club. They post monthly stories, results, and even map out months of meals that include things like steak, chicken, beer, etc. Diet programs do not work! The food they sell is just a tool to help you change your lifestyle, which you can do on your own and save money. Plus the food you make usually tastes better.