In the Setup program, the user can choose their sound effect card (used for sound effects like WAVs, and also for MOD and XM music) and their MIDI music card (used for MIDI music only).
They can also choose what screen resolution they would like to run the engine using. The available choices are 320x200, 640x400 and 960x600. The higher resolution gives a better quality picture in the game, but slows the game down. You can get an idea of which setting you should use for your system from the System Requirements page. The 960x600 mode is currently unsupported and should not be used.
Note however, that the picture quality is only as good as it was drawn, so if all the scenes in your game are drawn at 320x200, then using the 640x400 resolution will not help - it will just slow the game down. However, some graphics cards do not support 320x200x16, so choosing 640x400 will at least allow the game to run.
NOTE: It is possible to use 320x240 and 640x480 resolutions, as long as the game has been set up to run in 'Letter-box mode'. (which will in fact give full screen 640x480 for rooms of that size).