1.5 Core Solo, 1.66 or 1.83 Core Duo, or 1.83 or 2 GHz Core 2 Duo processor.
This covers the first Intel-based Mac Mini models from Early 2006 to Mid 2007.
We have an entire section of iFixit dedicated to repair guides. You should take a look at it while you're here. As far as the Mac Mini hard drive, we happen to have the exact guide you're looking for.