I use a Mac for most of my work. It's not a religious thing, any OS is after all just a means for getting something done, but the whole system works better as a unit for me. As one highly-paid industry analyst, whose geek cred is beyond question, said to me a while back: "My time is too valuable to waste screwing around with Windows." This is true, at least for me, even when the value of more time isn't measured by dollar billing rates.

I have a couple of apps, mostly Access, that require Windows. I use Parallels Desktop for those. In Cohesion mode, it's nearly transparent: when I get an Access .mdb or .accdb file, I double-click on it just as if it was a Mac app file, and Access opens in a Windows window on the Mac desktop. Much of what I do with Access involves going back and forth between the database, FireFox (on the Mac side) and TextEdit (also a Mac app); it's seamless. I can't avoid seeing Windows completely, since once in a while something needs tweaking there, but it's minimal.