I set my wife up on a Macintosh last week (with some serious help from the local Apple store), switching from a PC. She got the cool aluminum Macbook (I make do with the cheap white plastic variant). So far, she's quickly come to realize the benefits of a 2-3 second wake time from sleep mode, not to mention the speed of the applications. I reckon having been on a Mac as my primary notebook for a few months, that I save around 30 minutes per day, on average, not having to wait for the computer to wake from sleep, launch applications, reboot, etc. Mobileme integration (which synchs email, calendars and contacts across PDAs and multiple desktop/notebook systems) also saves significant time and costs far less than Exchange. All in all, a pretty cool total cost savings. What's not to like about it? PowerPoint for Mac is a wretched application in far too many ways to write about here, but you can always run the PC version if you're so inclined (by running a Windows environment on the Mac, which is easy).
QuickBooks Online also requires Internet Explorer, which requires Windows (but again, this is not a big deal). I also need a special cable to connect a monitor when I'm presenting at a conference or at a client (usually for these meetings, I bring another notebook, a PC, along anyway just to simplify things and to show I'm not a Mac bigot). Besides these few shortcomings, I'm thrilled. I can say with complete confidence that going Mac will save us over a thousand dollars per week in productivity gains. After all, time is money. And that makes the Mac a smart Spend Management decision for research and Office intensive environments -- particularly in consulting and publishing -- if there ever was one. If you close and open a notebook more than once a day, you'll wonder how you ever lived before making the switch.