lol, 3.1 and 3.11 rock! (remember those old ISA sound blaster 16 cards that just about every computer had back then, lol - I've got a cupboard full of them.)
I never really liked 95, it was probably to do with the fact that I went streight from 3.1 to 98SE. But I allways thought 95 was mainly lacking something. 98SE is the best! (still using!)
I like XP but too expensive to put on every PC. You can buy 98SE liscences fairly cheap on ebay now. (or just peel them off the computers at school

)
I remember I once got XP-Pro SP1 working on an old Pentium Pro (150mhz) with a 2.5gb harddisk and 64MB of old RAM (those SIMMS things). lol
Millenium Edition Sucks! I used it for four years. All of the pretty colours! You couldn't help but love watching the blue screen as your computer did a physical memmory dump every 5 mins!

(I heard once that microsoft employees were calling it Mistake Edition.

)
I remember that you could point the previous version search on old Microsoft upgrade disks (office 95/97 and Win 95) to themselves and it would install fine without a previous version of that program on the harddisk!
Commodore 64 were the best PCs ever and allways will be! (even though I hadn't even been born when they came out!)