The first step is to let Train Simulator Profile your video
card. This process will automatically adjust Train Simulator to
run best with your video card. You can make your own adjustments
later, but this is an important step.
Go to your Programs Start button and locate the 'Train Simulator
Troubleshooter' line and then click on 'Change Video Driver'.
That's all.
2. ALLOCATE SYSTEM MEMORY FOR TRAIN SIMULATOR
You can increase the memory dedicated to MSTS using the
added parameters to the program's target line.. For more info
on that you can check out the author's full tutorial: http://msts.steam4me.net/tutorials/xtra_mem.html
By right clicking the MSTS icon on your desktop, you
can alter the target by adding one of the following(in blue):
...train.exe" -mem:512 for
playing MSTS full-screen or
...train.exe" -vm:w -mem:512
for playing MSTS in a window

3. GET BIN
Bin is a 3rd party update to Train Simulator that we could
simply not live without! Download the latest version of Bin from
the website and install it. Make sure you already have the first(and
only) Microsoft update released in 2002 TS
Update 2002 before installing Bin:
COMPATIBILITY MODE
Another simple tweak you may want to make on your Windows 7 system
is running Train Simulator in 'Compatibility Mode'. Just right
click the Train Simulator icon on your desktop and select 'Properties'.
Go to 'Compatibility' and check the box for 'Run this program
in comptibility mode for: Windows XP(Service Pack 2) ...or experiment
with the other modes offered there.
I use the following settings on my Windows 7 machine:
MIGRATING MSTS TO ANOTHER HARD DRIVE