I switched my business in September.
The differences aren't as marked as you might think, and there are certainly areas of OS X that remain unpolished (like having to restart after most software updates - on a UNIX platform this just isn't necessary, it's lazy programming), but I've found OS X to be more stable, far more resistant to malware and an altogether more productive work environment.
You wont believe how much you use the Exposé show-all-windows feature! I haven't 'alt-tabbed' since September!
I'm thrilled now we're using CS3, so all our Adobe apps are Intel native, and I've zero problems to report so far there. Before, when CS2 applications were running under Rosetta (as they were created to run on PowerPC processors for Mac, not Intel), the applications used to be a little unstable - but they'd only ever crash themselves, not the host OS.
Office, however, remains an issue. Mac Office 2008 could be many months away yet, and the currently available version also has to run under Rosetta. It's quite stable, though not infallible, but pretty slow and outdated. Open source office suites exist that will suffice for many tasks, but not all.
Overall, the verdict is very positive. Keep your expectations realistic and you wont be disappointed. You and your staff will need to embrace a new way of computing (trying to 'make' OS X cater for your Windows habits is a non-starter - let your will be broken early, you'll thank me for that tip), but it's easy, fun, and you'll have a nicer computing environment as a result.
I hope that helps a little
Now all we need is Sesshi to come and give you horror stories about Apple hardware and we're done
While I'm on that subject - no, Apple doesn't have the same level of hardware support that a company like Dell has (no 4h on-site response or anything like that, not in the UK anyway). In terms of the hardware reliability itself, I've found it to be very good in comparison to others, particularly Dell, but others have had very different experiences. Surveys have indicated that Apple hardware is actually more reliable than its rivals, but to be honest everyones experiences are different and any good strategy for dealing with failed hardware will apply regardless of what vendor you choose.
