My 2010 MacBook Air is as good as the day I got it - How does Apple do it?

I have a 2010 MacBook Air with 1.86GHz Core 2 Duo Processor with 4 GB RAM and 128 GB SSD. This was my first Mac ever and the past 4 years with it have made me a complete Mac convert. I will never ever buy a Windows computer for personal use again. My 4 year old MacBook Air still boots up in 14-15 seconds and shuts down in about 5 seconds. It runs the latest Operating System (Mavericks) and has never once crashed. I may have restarted the computer less than 3 dozen times in the past 4 years and everything works as reliably and as fast as ever.

I don't believe a 4 year old Windows laptop with the same specs would come even close to maintaining this kind of a performance especially on such an outdated Core-2-Duo processor. My work laptop, which is a Dell M4500 work station, is being replaced after just 2 years because it is crapping out - it over heats like crazy, the NVIDIA display driver keeps crashing, and I am on my third HDD already.

The downside for Apple is that I am not buying a new computer any time soon, because my current one works so well...but my great experience with the Air has also led me to surround myself many other Apple products - iPhone, iPad, Airport Extreme and Apple TV.

Anybody have a similar experience with a Mac that led you to completely swear off Windows machines?