I'm at a little over two years now. I bought my Mac when my year-old Windows laptop died in the middle of a very important project.
My 13" Macbook Pro is still going strong, which is more than I can say for any Windows laptop I've ever had over that same amount of time.
I also went out and spend $100 on a Powermac G5. I bought it partially as a back-up for my laptop and partially for the $3000 worth of software the previous owner had installed on it(Photoshop CS4, Adobe In Design, and several others). That particular computer dates to late 2003. I threw 4gb of ram into it, as well as a pair of 1TB hard drives. Although it's a bit laggy on the internet(I think most due to factors related to it being an outdated and mostly unsupported CPU architecture) for "real" work it still is as fast as I could ask it to be. I think that's pretty impressive for a 10 year old computer.