Go into the Display Properties, click the Advanced button and then click the Adapter tab. Look for option to ‘List All Modes’…. if you get this far the resolution and 8-bit color you desire should be listed.
Or right click on the executable of the old app you are trying to run, and click "properties" then go to the "compatibility" tab and check "run in 256 colors" and "run in 640 x 480 screen resolution"