"We tried to put a whopping terabyte worth of storage in a Mac mini -- and succeeded!
This guide walks you through the process of replacing the stock hard drive and optical drive with TWO 500 GB hard drives.
Warning: Although you're welcome to do this at home, this surgery is at your own risk. Make sure to back up any important data prior to working on your mini's hard drive. We'll post more information regarding heat and performance as soon as we have it available."