To make the names of your desktop icons appear in black enter this in a terminal window:
defaults write com.apple.finder Desktop.HasDarkBackground 0The names will look appear like this.
defaults write com.apple.finder Desktop.HasDarkBackground 1(Of course you need to logout or kill the Desktop to see the changes)
Mac OS X Hints
http://hints.macworld.com/article.php?story=20010103111120333