Hello
Thank you for your answers. I'm a little surprised, it's three weeks ago...
I have Pentium Duo E8400 3GHz, Nvidia9800gt 1gb overclocked, 4 gb DDR2 800mhz 2x2 dual channel, monitor 19".
The settings in Nvidia Control Panel Manage 3D setting for Trainz are:
   anisotropic filtering   --------------------------8x
antialiasing - gamma correction   --------------global setting
antialiasing - mode  ---------------------------override any aplication
antialiasing - setting   --------------------------8x
antialiasing - transparency ---------------------supersampling
conformant texture clamp ---------------------use hardware
error reporting  -------------------------------off
extension limit --------------------------------off
force mipmaps --------------------------------trilinear
maximum prerender frames --------------------3
multi display/mixed gpu acceleration------------single display
texture filtering-negative LOD bias-------------clamp
texture filtering quality--------------------------high quality
texture filtering - anisotropic mip filter----------off
threaded optimization--------------------------auto
triple buffering---------------------------------on
vertical sync-----------------------------------force off
Any suggestion please