What is a good marathon training program?

There are many: Ive done 4 full marathons i believe that if you can presently run 20 miles a week, you can gear up for a marathon with a 16 -18 week program the key to the program is to increase the weekend long run in a gradual fashion so you get up to about 20 miles 2 or 3 times in the 4-6 weeks prior to the marathon. You should ease off the last two weeks so you will be fresh for your marathon.

Many options: All depends on your goal. If this is your first, then the goal should be to finish healthy and be able to move on to the next goal. Many programs available online and written. Go to barnes/noble and look through some of the training books. There are plans ranging from 3 - 6 days /week committment. Find a club. There are great ones in/outside philly: bryn mawr running club and fastracks (paoli).