My wife, a non-gamer, but who is willing to indulge my hobby got me Railroad Tycoon for Christmas -- the full English version. I had been thinking of getting Railways of the World with any extra Christmas money, but my wife surprised me. I know that RotW has changed the map (smaller and an additional New York connection), few rules and has new operations cards. What do I need to do to upgrade RrT? Or do I even need to bother?
Eagle/FRED is selling the newer maps individually:
But, by the time you buy those maps at $40 you're close to the going rate of $48 for Railways of the World.
Personally, I would put money towards Railways of England and Wales and Railways of Europe first (in that order). Both expansions are 100% compatible with RRT.