I voted Linux & Windows. Bet you never thought you'd see those two together now, did you?
Now in general, I have to admit what I'm about to say will be even more "wtf?"... but OS X is too simple. It's *boring* in its simplicity. Ooh, surf the net ("safely"), load some pictures onto it, pay £250 for Photoshop to edit them (cause no one warez's mac programs), etc.
Now, Windows. Gamez! (And warez, tbqfh). Lots of them. Fun. And it's fairly speedy, at least XP is. I'm not a fan of Vista. Actually I hate it so much I wiped this laptops Vista without even backing it up and put XP (dual-boot with Kubuntu on it) on. I think it's problem is that it tries to take some of Linux's ideas (prompt for password before format, etc) but takes it far too far. What's worse is that Mac users turn around at Aero and say "oh, we've had a UI like that for-ever!", when in reality both suck. It's like a speed-stripe on a car. "Oh look at him, he's cool. I'll be that makes his car go 10mph faster!" (When in reality Aero makes Vista about 20-30% slower, for some reason).
Anyway. Could be complaining about that forever. Why Linux? Cause it's fun. It doesn't even need games to be fun (although it has a few, UT and NWN, etc.). It's free isn't really an argument, cause I have so many XP licenses lying about from oldish PCs it's unbelievable. But in saying that, most Linux distro's have very easy package managers which give you access to a crap-load of software. I believe the entire Debian v4 release is 9DVDs big. (That's around 40GB of software, compressed, although you can download the 180MB install CD and be up and running, albeit in text mode
).
The reason, IMO, that adults don't like Linux was put impeccably into words at DebianDay for me last Saturday, by Knut Yrvin of Trolltech - adults try something once, fail, and then are like "ffs this doesn't work". Children try, fail, and then try again, and succeed - maybe on the second, or even fifth retry. But the thing is that they keep at it and overcome the problems in the end.
For those holding out on Linux, go buy (or warez, for the Windows users
) Acronis DiskDirector Suite, resize your NTFS partition to half, then download Ubuntu Linux 7.04 and install it in the free space on your hard disk. You won't be disappointed, unless you're stupid. Or an adult that only tries once. Although you may get it on the first try.
Kay, I wrote an essay when I didn't mean to. But I think I got my point across.
End note: ATi are now owned by AMD so they may get better. Although both AMD and ATi are currently trailing in the markets. ATi Linux drivers are the equivalent of a two year old driving a 10 ton truck. ATi Windows drivers are better, however they're not quite as good as nVidia's Forceware package, but I've had both crash on me and do other horrible things.