Are you running Windows XP ?
If so, then right click on the short-cut for the game, and select the "compatibility tab" There you will see the features for screen.
If running windows 95/98/2000
right click on your desktop (no icons), then select the properties option from the pop-up menu. Now click settings. there you wil lsee a slider. move this down. Next to the slider you will see "resolution etc" select lower settings.
Remmember: You have to manually set these values back!
NOTE: running these old DOS games under Windows XP etc is not really recommend, they tend to hang the system, poor or no-sound is also a issue.