This airport has an excellent express train service to Central Station in central Stockholm.
This excellent Express railway service is called Arlanda Express. It take you non-stop between in the airport and Stockholm central railway station in 20 minutes in 2002.
And there are plenty of train availabe a day.
You can also use this train to get to the airport. Just make sure at the airport you get out of the train at the right terminal.
2747.com - Up