DOS-based machine with no HDD, used 5¼" and 3½" floppies - 1993 or 1994, my mom got it through a correspondence course, and we weren't allowed to use it too much.
Windows 95 NEC, Pentium 166, 16 MB RAM, CDROM - 1995 or 1996, family computer for about 5 years, moved into my room, and then into my sisters' room. Used it for word processing, games (including Sonic CD and Starcraft), educational type stuff, etc. We still have it, although it's blocked by a bunch of junk.
Windows 98 Compaq, no clue about specs - 2000, family computer for about 3 years. Piece of crap. Would take half an hour just to boot up (even that Win95 we had took just 5-10 minutes). I took the DVD-ROM drive out of it just before they junked it and popped it into my computer.
eMachines T1110 - 2003, hand me down from my grandfather. First computer I myself have owned. Posting from it right now, actually. I listed out everything I've done to it over the years in a post a day or two ago. You can see the list here:
http://www.christianforums.com/t7483913/#post55266785
They've gotten more computers over the years, though - an eMachines in 2003 (which they still have in the living room) to replace the Compaq, an Intel iMac running Tiger (now Snow Leopard), and my mom got an iBook in 2002 and an HP laptop that runs Vista in 2007 or 2008. I'll likely be building my next computer.
This is of course discounting the fact that my school had a bunch of Apple II's (pretty much only good for playing Concentration and Oregon Trail) and early 90s Macintoshes for the students to use when I was in 3rd or 4th grade. There was also a take-home program that I remember we were part of, and got to use some type of early Mac...couldn't tell you what one, though. But it had screen reading stuff on it (could not pronounce Connecticut unless you spelled it phonetically, and even then it still sounded weird). The screen on it was probably about the size of netbook screens now, but of course a lot clunkier.