MSTS Demos

I don't think there's ever been an MSTS demo, if you have a look in your local game shop you'll probably find the sim in the bargain bin for a few dollars.

If you want a new sim though you're probably better off just waiting for KRS or MSTS 2 rather than buying buggy six-year-old software ;)

I would imagine there are quite a few clips of MSTS on You Tube to assist your considerations.