I went from a Windows Vista to a Mac environment last year, primarily for the matte screen on the 17" Mac book pro. I travel and do consulting for a living so it took some work to get everything working on the MacBook.

I run VMWare Fusion on Mac Snow leopard with a Windows XP image. It works great and allows me to both access Mac and Windows together.

I also have BootCamp with a full Windows 7 install, to run more intensive MSFT programs like SQL Server. This works well too, the only major negative is that sometimes it requires a reboot to get to a file that's on the other image.

Pros:
- Mac OS is pretty good, easy to do many things
- Hardware is awesome

Cons:
- I'm more comfortable with Windows and don't really know how to do many things in Mac (I need to take a course at the apple store)
- File management - have to be very strict on where I store things to keep files in order, especially for multiple clients being run across Mac OS, Windows XP, and Windows 7.
- Cannot play any kind of games in VMWare Fusion (not a huge con)
- Windows smart phone will not sync correctly with VMWare image

Overall I would do it all again just for the beautiful hardware.