Most of my machines are set up to dual-boot: Windows and a 64bit build of Ubuntu. I find I rarely boot to Windows though, since Linux in general is such a good development environment.

/vim?/, Geany, git, perlbrew/perl, gnu g++, MongoDB, PostgreSQL, MySQL, and cpanm/CPAN are about all I really use frequently enough to consider them a part of my "development environment".

I really wish that I had a copy of Windows that wasn't pre-installed on my system, so that I could forgo the Windows partition, and just run Windows in a VirtualBox from Ubuntu. That way I could still use Lightroom, and occasionally VisualStudio without rebooting away from my preferred dev environment.