But I personally hate it's green color.... lol
use one of the resource extraction tools to get the progress bar bitmap from luna.msstyles, recolor it, put it back and restart the system.
i am boring people by repeating this but go get the theme you'd like (try destiny, opus-os, clearlooks, royale/noir, zune) - don't immediately consider changing something just because you don't like it on luna (xp default style) with blue color scheme. my progressbars are orange.