Free png and vector icons by Iconlandia

Full and empty folder icon replacement pack. 6 colors. 12 different icons.
PNG & ICO sizes: 16px | 24px | 32px | 48px | 72px | 96px | 256px | (512px PNG ONLY).
The .ICO files have all the sized icons within them. All you need to do is select the .ICO file you want to use, and Windows will do all the scaling itself.
Free for non-commercial use.