There is TS09, TS10 (which are unsupported now)
And N3V's TS12 which will be supported for some time beyond the release of T:ANE (when ever that is).
N3V's TS12 works with a 32 bit OS, as does TS10, TS09, TRS2006, and TRS2004.
You can still run 04 and 06 (with allot of meticulous backdating of assets config files).
Soon ... TS09 and TS10 will also require with allot of meticulous backdating of assets config files.
Railworks is also called: "Train Simulator 12" and "Trains Simulator 14" bought in Big Box stores like Target and Walmart, and these are Steam products not affilaited with the N3V Trainz Simulator.
If I were to buy TS12 I would recommend buying from JointedRail or N3V's SimCentral, the official distributors, and I would shy away from buying TS12 on the "Steam" website. and would totally shy away from BigBox Stores.
Buying on EBay and Amazon is not recommended as you will most probably get a "Steam" version ... or a previously registered game, which can not be re-registered again ... or you will end up buying a Non-N3V product that is a totally separate entity called Trains Simulator 12, which is Railworks ... which is not supported or connected to N3V's TS12 Trainz Simulator.
Trainz and Railworks are not compatable, and are totally separate entities.