I have a 2007 model mini and it's been running OSX server/10.7.2 since then until now. It's got 3GB ram and I removed the CD drive and put a SSD in behind the slot for the OS and it has a 1TB drive where the standard 250GB one was.
Still going strong and running 24/7. It's the max it can go but a massive improvement on the original specs it had.
Edited by ZenUserJP (Mon 05-Oct-15 22:40:04)