Here's an article and PDF that everyone should check out about LCD burn-in:
http://www.dslwebserver.com/main/lcd-screen-burn.html
http://www.necdisplay.com/support/css/Techlibrary/Image_Persistence_White_Paper_0505.pdf
http://www.dslwebserver.com/main/lcd-screen-burn.html
http://www.necdisplay.com/support/css/Techlibrary/Image_Persistence_White_Paper_0505.pdf