I've become a fan of parallels the virtual machine emulation software for the mac.
At first I thought it was ok, having built a xbuntu machine, but it had a couple of bugs regarding the operation of shutdown and hibernate. Fair enough. A useful toy but that's it.
Then I had to build an XP and 2003 machine to do real work - and suddenly its power was revealed, cutting and pasting from the two operating systems, and flipping between the two, even if I felt there was something ever so slightly unclean and dirty feeling about building horrible clunky crude windows on my elegant mac - it also shows how in 12 months of being a mac user I really have become a mac user, and while linux is an alternative, windows feels crude in comparison - singularly lacking in elegance.
But hen windows didn't get 95% of the desktop market by being elegant. However I digress ...
Parallels is a fantastic tool. The only failure I had was building an old version of collecge linux that didn't recognise the virtual disk as a valid system on which build the system - not a great loss, just the comfort factor of using an old distro that I like, I could have done kubuntu to get the tools.
Free BSD isnatlled almost nicely, but then I'm not a free bsd person so that's me, not the oS