I am planning to do a roadtrip from San Fran,ca to Philadelphia, this sep 08. I have 3 days to do this. help?

Plan for some very long nights. I have driven from Boston to Seattle and from Orange County to Boston twice. each trip took me 4 days. For safety I would plan to add a day to your driving. Especially since you will be taking the northern route which let me tell you is hypnotizing by its flatness and boringness.