OS of choice: whatever I'm using. That said, I don't know BeOS, TheOS, Minix, AIX, etc....
I prefer FreeBSD, but I can't play many strategy games on it. The real world is slightly deceived about what computers ought to do vs. what they want them to do. It's nice that they can do all this entertainment schtick, but BION they'd do better IMO to give us all the details and let us fix the stuff ourselves.
I have 2 desktops (FreeBSD && Win98SE) on a KVM switch at my desk. Across the room are some more boxes which run either of these OS'es depending on which HDD is slapped in them at the time, and usually at least a couple of broken winboxen I'm trying to revive for someone. In the house is WinXP Home, which is better than 98, of course, but still gives occasional problems which seem to be more cryptic to decode and fix than anything was with 9x. It could just be that I've not spent as much time fixing XP machines, but I like a quote from ST's Mr. Scott --- "the more they overthink the plumbin', the easier 'tis to stop up the drain..."
My (dead) laptop is XP Pro; I do kinda miss having the laptop. Hopefully the extended warranty people will hurry up with the ** thing... which brings us to l/d: desktop is preferable; laptop is portable. Where have I got to go today?!!
My BSD desktop is AMD 1800+; the win98se box is a K62/475, IIRC. I'm a gadget freak ("oh, it's got an automatic discombobulator on the network card AND a built-in doomflitchie? Cool!") but I'm not that performance oriented (if it works, good enough, a few extra milliseconds aren't that big a deal, 'cause there's always something to do while it's booting or whatnot...)
And yeah, I'm kinda with Norman G. What does this have to do with real education? ๐
Good luck!