this is what the apple site says about cleaning:
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TITLE
How To Clean an LCD Panel
Article ID:
Created:
Modified: 60446
7/30/99
5/30/01
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TOPIC
This article describes the best way to clean an LCD panel such as those used on PowerBook computers and Apple flat panel displays.
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DISCUSSION
To clean the LCD:
1. Turn off the computer or display. You may need to turn off the computer in order to turn off some Apple displays.
2. Dampen a clean, soft, lint-free cloth or paper with water only.
3. Wipe the screen. Do not spray liquid directly on the screen.
You may also use a mild glass cleaner that contains no alcohol or ammonia. Most office supply stores sell cleaning kits specifically designed for this purpose.