My first was an i386SX (Intel 80386SX) based machine running DOS, and mind you I was only 11. Damn you people are old!
Memories:
Apple 2E: BRUN FID, CHOP LIFTER, Castle Wolfenstein
C64: INFOCOM Text Adventures, Scott Addams Adventures, 300/1200 Baud Modems, BBS', D-Dial, one of the first multi user chatrooms, copying games for your friends, Tape Drives.
Amiga: Awesome games. Slow for everything else.
I like how my iphone out performs all of those puters. Crazy how fast technology moves.