WinXP at work, Vista and Win7 at home, so it’s a clean sweep.
I use a Mac at home and Ubuntu at work, so I am pretty evenly split. I borrow use of a Windows machine once every fortnight because our timekeeping software at work only runs in IE (and badly, at that)
In one sense I use Windows exclusively, because I have Windows PC. But I spend a lot of time connected to computers running various forms of Unix and VMS. It would be difficult to break that down to percentages, but Windows would still be above 50% because I can work on most things using a compatible Windows form of software locally. Most of that is irrelevant because I work primarily on platform independent software and rarely concentrate on the OS specific code.
You still occasionally see job openings for folks with VMS, IBM 370, and similar type experience (presumably for maintaining old code). Or I suppose that you could be relatively computer-free, and just use a PDA OS like iOS or PalmOS for your day-to-day computing. But I agree, I don’t think that poll option’s going to get much off zero.
OpenSUSE ( or OpenSuse, or Opensuse: the name appears as variable as the pronunciation ) linux.
Macbooks running Snow Leopard, both at home and at work.
I use Macs for all of “my” stuff, but the point-of-sale system at my bookstore is Windows, so I do actually use both.
I run Linux on my desktop and PC-BSD on my laptop, so I guess I’m one of those mythical “other-OS-using” people you guys are wondering about.
Dual-boot Ubuntu and Mac OS. But it’s at least a 90–10 split, respectively. Especially since I haven’t upgraded Mac OS in ages, so it’s too early of a version to run things like Google Chrome. Meanwhile, Ubuntu gets upgraded every April and October when new releases come out.
Solaris, with Windows and Linux VMs as necessary.
Windows XP Home Edition Service Pack 3.
As for a non-*nix “Other”… how about Haiku? 
I develop for Windows and currently only run that.
Hello, my name is Jasg and my household has an iOS problem…
Three adults, one toddler and 6 iOS devices (3 iPad & 3 iPhone). One laptop with MacOS but main computer is Win7 Ultimate. One lonely Android phone…
Vista user. I’ll be getting a Win 7 laptop when I’ve got the money.
I’m still on Windows XP, at home and work, and one of my netbooks.
The other netbook is Xubuntu Maverick Meerkat, but I’m not on it enough to be ‘primarily.’
WinXP for work, OS X for home, and I have several Linux boxes here and there at home and at a couple of nonprofits that I maintain.
All of the Linux boxes are older hardware running one of the Ubuntu LTS releases (Long Term Support).
I’m Mac. I would say in my circle, it’s probably 75% Windows, 25% Mac, 0% Linux/Other.
7% Mac? That seems like an outdated stat. It might’ve been true pre-2005, but now I’d double that at least, maybe triple it to 20%.
Exclusively Linux at work, and exclusively Mac OS X at home (now - used to have Windows up til a year or two ago).
I’ve never owned a non-MacOS machine and except for a very brief stint as a college workstudy student circa 1992 or so I’ve never had to use an employer’s computer as part of my job. (That’s got to be highly unusual, right?). So primarily MacOS by about 98% to 2% and a lot of that 2% has been in emulation running on a Mac.