I don't know about being able to change the font colour of the folder wording - but you can customise the appearance of the folder.
a) Right click on the folder
b) Left click on properies
c) Left " customise
You then have the choice of changing the folder icon, or importing a picture for it.
I use this quite often in order to highlight particular folders, and to make them stand out.
The aboce applies to XP Home.