There is a circumvesuviana stop in Vico Equense so you can get to Pompeii and Herculnaeum from there. Maybe the town is not by the train stop, but it doesn't look like much is there. I'm not sure there is ferry service to the Amalfi coast fron there?
Sorrento is the best transprot hub for both Pompeii and the Amalfi coast.
I have often though Sant'Agnello one stop down from Sorrento on the train also looked like a nice and cheaper place to stsy and it it would close to Sorrento's port. Besides the Circumvesuviana, there are buses between Sant'Agnello and Sorrento.
Edited: 11:04 pm, June 18, 2010