GParted — amazing stuff!
Well I have just finished partition my external hard drive with GParted.. however not without the gatcha!
Insert your hard drive to your laptop/PC
Make sure you UNmount the drive first before continuing. This got me and was getting some strange errors when i was applying the changes.
Now go back and clear (delete) everything from your external hard drive. (of course this is only necessary if you want to wipe everything in your drive incase its not as new!!)
Create your new partitions as preferred. I used the xt4 for file system..
Apply your changes and let GParted do the rest.