If you mean MSTS 1, I can't help at all on that...Fabian is the best man to go to for that...

On the other hand is Kuju Rail Simulator, it's been out in Europe for around 4-5 months now, but only came out in North America on the 18th of January.

If you're looking into a long term investment, look into Rail Simulator. The default locomotives are so nicely modelled, you'll have to wonder what add-on developers will come up with. The game has great potential. You'll have to give it some time though...Patience is a virtue