There's been some major improvements on msts since it was released in 2001. Here's a list of the top three (in my opinion anyways) that are needed,

There are two on this page from Microsoft.
Main page in case there's somethin else you might want

http://cgi.ebay.com/MICROSOFT-TRAIN-...item2555b7c536

This update makes the SD40 drivable and adds a few rollin stock to the game

http://download.microsoft.com/downlo...ent_update.exe

This is an update to the game exe. itself. This is an importrant update

http://download.microsoft.com/downlo...rainupdate.exe


This one's important also. The MSTS Bin Update is a 3rd party update developed for MSTS. It has enabled many new features, previously unavailable in Train Simulator. BUT you MUST have the updated exe from ms (posted above) installed to use this one.

http://mstsbin.uktrainsim.com/eng/eng.html

Click on the download button on the left