my most memorable expirience was when I broke my step-dad's work computer, then panicked, and re-installed the OS to see if that would fix the problems. About 1/5th of the way through, I suddenly realized that the re-install might very well wipe the drive and all the files....and then my step-dad pulled into the driveway.
Sweating bullets for the last 10 minutes while hearing him walking around downstairs, and I'm not even sure if I've just deleted all of his work papers.....
The computer finishes, reboots, everything is there, everything works, the OS is back, and no files are missing. Put the disks back on the shelf and head downstairs.
This is when I first became a macintosh lover. When re-installing OS 7 was simple enough that my Step-Dad never found out what I had done.
The *first* memorable expirience was when I first sat in front of a computer - an Apple ][e w/ a text-based RPG on it (left,left,right,left,right to find a super sword!). My Mom got rid of that machine one summer while I was away at camp. She kept all the disks, but got rid of the machine. A lot of good the disks did me without a machine to read them :\
The last was when I went from a 66mhz machine to a 266mhz machine, and 1 hour RayDream renders dropped to ~6 minutes. The G3 processor was SO much faster than the 601e.