Mine was the 1st generation, the original G4, introduced in January 2005. It was also the first computer I owned. I got it about June that year, so I could do more work at home rather than having to use the computers in the office on campus. With no phone line, it was a couple of years before I got connected to the internet, using "mobile broadband". My second Mac Mini was the 7th generation early 2009 model. With an additional 4 GB of RAM (now 5 GB), it still works fine for me. With a further upgrade to Yosemite, along with an SSD and 8 GB of RAM, I reckon it should be good for a good while more.