I'm not to familiar with Intel, but I suppose that is the 2,8GHz dual-core, in which case should be sufficient itself. The 8500GT and only 512MB of system RAM on the other hand, is a bottleneck.
I was running TRS2006 on that video-card in an old computer with 1GB of RAM and it was choppy alright. Changing later to a 8600GT and 2GB RAM made a huge difference and the latter wasn't a high-end card at all.
So for your sake - a better video-card (ATI or Nvidia) and atleast 2GB of RAM providing your PSU has enough power. Even then Trainz will sometimes be choppy, depending on how dense the route is and how many trains you run. Trainz is open ended and is able to kill almost any computer. Further more, TRS2006 somewhat choppy code has been refined in TC3 - 2009 - and even better in the 2010 version.
(Still running 2006 now and then, dunno why, but I like it...)
