Nokia Map Loader only works on Windows, requires.net framework, and if you add a new map the map loader deletes all your existing maps so you'll have to download them all over again.
But you don't need Nokia Map Loader! http://nokiamaps.moo.no links to all maps directly on the Nokia/smart2go server. You can download them using any browser on any operating system of your choice. There's no need to install anything on a computer: perfect for Mac or Linux users, or for when you're on the road and you can't install any software, like in a hotel, school, at work, or in an internet cafe.
If your phone talks WiFi or if you have a fast 3G connection you can even use the web browser in your phone so you can add and update maps without even touching a computer.
Get maps for Nokia Maps without using Nokia Map Loader: http://nokiamaps.moo.no