I have always used the memory switch set to -mem:1536 because I had found out that Bin had made it possible for MSTS to use this much memory. Is does make a difference. The upper limit for WinXP is 4Gb (well around 3.6MB) Follows is a recap of the target line switch parameters if anyone is interested:
The switches can be used in combination eg...\train.exe -mem:1536 -vm:w
"C:\Program Files\Microsoft Games\Train Simulator\train.exe"
...\train.exe for playing train sim in full screen environment
...\train.exe -mem:1536 for playing MSTS full-screen with memory allocation in megs per Bin modification
...\train.exe -vm:w for playing MSTS in a window
...\train.exe -perflog for creating a performance log file in root directory of Train Sim
...\train.exe -toolset opens msts editor
****NOTE: forwardslash used on following switches***** these are used AFTER any parameter switch containing a - minus
...\train.exe /timeacceleration opens with time acceleration feature
(Ctrl+T increases and Ctrl+Shift+T decreses time acceleration)
...\train.exe /anisotropic activates anisotropic filtering if supported by 3D graphics card
...\train.exe /fsaa activates full-scene anti-aliasing if supported. Adding this switch renders the view at a higher resolution and then samples it back down to the resolution you have chosen--it can slow down performance quite significantly but can also reduce jagged edges and improve the general appearance of the view.
...\train.exe /fsaa /anisotropic activates both full-scene antialiasing and anisotropic filtering. Adding this switch
improves the filtering used to render the textures, particularly on polygons that are almost perpendicular to the screen.
Note: Be aware that by using a shortcut to train.exe you bypass any options selected in the Troubleshooting menu. If you
need to reproduce the effect of these options you can add the following switches: all the parameters
/forcemaskz -- Smoke displays in block form.
/pixbias -- Text displays in block form.
/maxtex:256-- Textures are distorted.
/nofiltercab-- Seams are visible in cab cockpits.
/ttfblitfix -- Text is distorted or not displayed.
/skipsizecheck -- Skip texture size limit test.
/skipbiascheck -- Skip pixel behavior text.
/simpleclipping -- Snow causes game to crash or does not display.
\train.exe /fsaa /nofiltercab Depending on the precise implementation of full-scene anti-aliasing on your 3-D card you
may see a seaming or tiling effect in the Cab views, in which case adding the switch /nofiltercab may help.
Some of the above are from old posts on the MicroSoft Train site pages