hello my first real computer i started using was actually this macbook i haven't really been really into comps for more than a year or so :D i really am interested in comps now though but that's the first one i really used and was mine :)
My first "computer" was a Commodore64, it had a cassette tape drive and a floppy drive. Then I had a Texas Intstuments soething or other, then an apple IIe, then I skipped forward a while and got my first 80286 don't reember who made it tho. In between the break of the apple and the 80286 I used to use a friend's 8088. After all that I just followed the progresson of intel 80xxx computers up to my 80486, and eventually to my first Pentium system. Now I have a couple Pentium 4's and a couple Core2Duo's in use.. man I'm old...
My first was a Commodore vic-20, then a Commodore c-64, next a Commodore C-64/128, And finally a 100mhz Packerd Bell (Windows95) over a 5 year period back in the mid-eighties.
My first computer was an Amstrad Computer ( lol it used to use cassette tapes for games) no idea what the OS was, i think it was tho. After that it was an Amiga 1200 with its floppy disk games hehe (still got that). Then came the great AST PC, with its huge 8mb of ram and cd rom drive. Fun times :)