It's a bit OT, but I think it's great to glue the moldings. Then you avoid all the problems with holes and colors, and you don't have to start crying if it's a plastered wall where the nails just crumble the wall. I use this:
http://www.pattex.se/gor-det-sjalv/produkter/no-more-nails.html
http://www.pattex.se/gor-det-sjalv/produkter/no-more-nails.html