There is only TRS2006 (which is unsupported) (There is no TRS2008).
There is TC1&2, as well as TRS2004, but they are also ancient, but do work very well (look at Mezzoprezzo TRS2004 screenshots)
I still use TRS2006 extensively in surveyor to build routes, and import them into TS10. (TS09 is a version pre-released to TS10).
While TRS2006 surveyor is super user friendly ... with the CMP you will spend countless hours backdating assets and dependencies that have been updated beyond trainzbuild 2.6.
You can still download in TRS2006, but you need to buy a FCT (a 1 year FCT costs @ 0.06 cents per day), and or a higher version of Trainz.
TS10 will run on my Toshiba Satellite 105 Laptop, but the framerates are absolutely horrible (below single digits), as it has integrated graphics, and an Intel 1.73GHz CPU .