My solution to use the abr brushes in gimp.
For Gimp-Users with similar error:”…unable to decode abr format ….”
With abrMate you can open the brush-set and export all brushes to .png
http://www.texturemate.com/abrMate
With this gimp plugIn: Export Layers
http://registry.gimp.org/node/28268
all layers can be saved as Gimp .gbr brushes
