Bootcamp all the way. Ran a 12-seat company on them for 3 years. Still run 2 of the workstations 3 years later. Nice things about the (old) Mac Pro compared to almost any Windows machine: looks, build quality, near silence, efficient cooling, plus you could put a Mac-friendly cheap graphics card in and a real beast for Windows.
Right now they stay in Windows 98% of the time, running Softimage and Redshift, with Titans for rendering. I don't expect to be able to do the same for the new ones any time soon -- unfortunately, AMD/ATI cards are useless to me.
