you can find the spec's at the Trainz Classics WebSite + plus a lot of other info
If you can run 2006 there will be no problem with Classics
infact from what I have gathered it will run better
but from the spec you quote it will be just and not so fluid
you need more ram to be sure( 1 gig ) and a graphics card with dedicated ram around 128 MB and the latest drivers installed
with 512 ram - what windows needs theres not much left
