http://ffxi.gamerescape.com/wiki/Graphics
This will tell you everything you need to know about using the Registry Editor to tweak FFXI.
If you're not comfortable with doing that, and wish not to use Windower, then there is an alternative for you.
http://www.ffxicalculator.com/
Quote:
Please Note: FFXI Calculator does not make any attempt to interface with either the files or applications of PlayOnline or Final Fantasy XI. As a result, running and using this program is not against the Final Fantasy XI ToS. Furthermore, FFXI Calculator will not scan or record any information, interface with any internet-capable application, or make any attempt to connect to the internet other than through user-approved update checks. You can rest assured that this program is safe and free of any malware.
Not only will this allow you to adjust the settings for FFXI, but you'll get a wide variety of calculators that you can use to personally keep track of your progress in game.