I've found that you can play the Traffic Control simulations without DosBox on Vista, but that the sounds are distorted. Using DosBox, which emulates a SB16 card, you get the proper sound distinctions which may be a bit more important in some of the simulations. However you lose the ability to change fonts and font sizes (courtesy of the options in the Vista Command Window) which allows you to set a decent window size giving a clear and sharp display on a large LCD monitor (you can still go 'full screen' but the image tends to a bit fuzzy on LCD screens). These font options are not available using DosBox, at least as far as I can make out. Changing your screen resolution may be an option if you want to run the simulation in a window, otherwise if you stick with a high resolution (1280 or 1382 and above) you'll get a fairly tiny window if you don't opt for full screen.

You'll need DosBox for the Signal Box sims (or anything that doesn't use a character set for the graphics).

JohnT