There are some plugins already designed with your situation in mind, here is a couple:
http://www.lotrointerface.com/downlo...-ChatEdit.html
http://www.lotrointerface.com/downlo...rAdvanced.html
You can also change the font color & size of your game chat without plugins, in the Option panel; Chat. I hope it helps.
There are also many UI skins that change the color of the background on windows:
http://www.lotrointerface.com/downloads/cat2.html