Most of the pythonistas I know are more or less evenly divided between Mac and various flavors of Unix. Windows users are somewhat rare, but present. I was curious if other groups have different profiles.
Server side on the other hand I'm all *nix all the time.
I like the dualboot nature as when in debian I have no excuse to startup a game and get distracted, when in windows I know I'm off work and I can relax.
Also having access to good command line tools is priceless - I'm not conversant with powershell, so maybe windows is good for this now, but being able to quickly grep/sed/awk/vi/etc is so useful.