Found a solution, which does not require the user to update the graphics processor! Follow this simple process:
1. Go to your X-Plane 10 Folder
2. Access the 'Aircraft' folder
3. Enter the 'X-Aviation' folder
4. Enter the ''IXEG 737 Classic' folder
5. Scroll down and open the 'IXEG_user_prefs' text document
6. Within those preferences, you can alter settings that you couldn't have previously adjusted in the sim, by simply changing the '= number' alongside that command, e.g., 'steam gauges=0' is the default setting, however, if you change that to 'steam gauges=1', and save those preferences, the next time you open X-Plane, the steam gauges will appear in place of the modernised centre instrument panel. NOTE: For this to work, you must re-open X-PLANE subsequent to adjusting these settings.