My first computer was given to me in 2nd grade. A Mac 128k (the very first model with the signed internal case) no less. Later upgrade to a Mac Plus, a few others and finally ending up with a Power Mac 6100 running I believe some version of OS 8. I switched to Windows 95 in 1996 though (in my 2nd year of college) and never came back for years despite watching attentively as Steve Jobs returned to Apple and every keynote he ever made.
I shifted my parents to a G5 iMac in 2005 when I couldn't stand doing yet another clean reinstall of Windows XP which they got hosed up one way or another and just loved it. The moment an intel iMac came out with the hope (not yet promise) of being able to dual boot I switched back. In late Jan, early Feb of 2006 I came back with the first generation of Core Duo iMac. Still working as good as the day I got it... and tomorrow it gets 2 GB of RAM, a shiny new 500GB external drive (to go with the existing 250GB internal and external drives) and OS 10.5!
As soon as either a new Macbook or even a speed bumped Macbook is announced in the next few days/weeks my Dell laptop will also go the way of the trash and I will be an all Apple house again at age 31 from where I started in 2nd grade with the Mac 128k.
