Hello TravelingChick. I travelled in trains from Oslo to Stockholm, in May of 2007. That train trip can be done in 6 hours and 30 Minutes. It was pleasant, 2nd Class train cars in Sweden are pleasant (my train car had royal blue upholstery with bright yellow trim). Luggage racks above the seats (a duffel style bag can be placed on the rack) and the usual shelf for suitcases in a rear corner of the train car. That part of Sweden has flat land, no spectacular scenery, but I liked it : pleasant farms, some trees. In Norway you will see big beautiful fir trees (long needles) near the railroad.
During that ride, you could ask a Norwegian person to teach you to say some Norwegian words. Norwegian and Swedish people speak English fluently, and most of them are friendly to Americans, and they like to answer questions about traveling in their country. Is there any reason why you would not want to go to Oslo ? If, at some time in your trip, you will be in a train that stops at Goteborg Sweden, I recommend getting off the train there, if you have time for it. Goteborg can be a better city for meeting Swedish people, than Stockholm. (Swedish people in Goteborg said Stockholm is stodgy, stuffy). And Goteborg has places that are of interest to tourists. If you think you might go there, read about GOTEBORG in the book "INSIGHT GUIDES : SWEDEN".