Get in Pompeii from Rome

There are  so many people who would like a day trip in Pompeii when they are in vacation in Rome. The most easy but also more expensive way is by limo service, but they will spend more then 2 hours on the motorway.
Use public transportation is less expensive in the link www.rometopompeii.altervista.org, there are not just transportations info as trains, but also suggestion how to visit this famous archeology town, how much it will cost, discounts, guides, and much more.
To spend a week in Rome without to see Pompeii, is the same of to get in Venice without to see San Marco square