I'm not sure of the specifications of the first computer I used (I was only 4-5 years old) but I remember it was a Windows 95, and I played Commander Keen, Pinball, Cosmo's Cosmic Adventure, and a lot of other Atari DOS games on it I wish I could find the software again, but I remember my little brother breaking the disc in half... :'(
The first computer that was mine is the one I have now. My IMac G5 with Power PC. The computer I ever used was way back in elementary school and it was an old school macintosh that used the hard discs (cause when it was made there was no cd or dvd drives-and no cd's or dvd's).