I'd have to go back and look, but as I recall, if you'd bought a Mac in 2005 you would have lost complete support for Snow Leopard. Which was substantially shorter than 2007 > 2012.
hmm. I'm pretty sure it was just the powerPC macs that lost support for SL.
All Apple Intel-based computers were released January, 2006 or later. So any Apple computer purchased in 2005 would have been a PPC computer.
Due to release dates of some of the Intel models...some PPC computers did continue to be sold into 2006. For example, the last Powermac G5 model wasn't discontinued until August, 2006.
- 2005 = All Apple computers were PPC
- 2006 = A mix of PPC & Intel models were sold
- 2007 = All new models were Intel (possibly some PPC models were sold as refurbished)
Believe it or not...Snow Leopard (OS 10.6) wasn't released until August, 2009. So until early August, 2009...ALL Apple computers (PPC & Intel) were running OS 10.5.x or lower.
Another (believe it or not). The original shipping OS for a 2007 Mac-Mini...was Tiger (OS 10.4.10)!

That would mean that a 2007 Mac-Mini (if it were compatible with 10.8 Mountain Lion)...would be compatible with 5 major OS upgrades (this doesn't happen very often)...10.4, 10.5, 10.6, 10.7, and 10.8 (if it were compatible with 10.8).
I'm just mentioning this for clarity.
- Nick