You can set screen resolutions on widescreen laptops to eliminate distortion in MSTS: most in-built graphics card have an option to set "scaling" or "aspect ratio".
This is an example using an Intel Graphic Card.
Right-click on the desktop, select "Graphics Properties", then "Display Settings", thus:
Under "Display Expansion", click on "Aspect Ratio Options" (arrow #1 above).
Select "Maintain Aspect Ratio", thus (arrow #2):
This will give you the largest possible MSTS viewpoint with black bars down each side of the screen (much like a 4:3 TV programme on a wide-screen TV) - note you now DO NOT need the -vm:w parameter (see below):
Set the screen display in MSTS Options to the largest option available and save: MSTS will open with that resolution every time.
Command-line switches are useful if you have mini-routes that you want to run at a different resolution to your master MSTS as mini-routes take their initial resolution settings from the registry - UNLESS they are specified in the command line (for example, you're working on an activity in a mini-route and want to be sure AE opens in 16-bit to avoid "issues").
Here's another example using an nVidia-equipped laptop display: right-click on desktop, select "nVidia Display" then "Laptop Display". Select "Digital Flat Panel Settings" ans then select "Fixed Aspect ratio scaling".