I swing both ways ... I've got a couple of pcs running windows, and I've got an imac G5. The imac was bought to go in the built-in kitchen desk area so that my wife would quit using my laptop when she wanted to check email and surf.
(she's got some weird magnetic field that ruins electronics after prolonged exposure ... I swear, after about 2mo whatever electronics that she uses on a daily basis start to malfunction and eventually die.)
The laptop that the imac was supposed to replace has since died and I keep coming back to wanting a macbook or a mbp as it's replacement. The hardware designs are just so much more elegant (with associated issues) than what the big box drop shippers like Dell can come up with. Sure, they cost a bit more, but from what I've seen with my imac compared to my other windows based pcs, I can also run that hardware productively much longer. And now that I can turn it into a windows pc if I really feel the need, that's a deal clincher.
My OS X complaints:
1. You get conditioned to having to wait a bit for things; os x is never as "snappy" as a fresh windows install. But it never slows down with time like a windows install either.
2. 3rd party Software not as "mature"? Hard to describe. OS X still feels like windows 98 where you had to have all those little favorite shareware apps to get things done that you want to.
What OS X gets right:
1. Program installs. Mount the dmg, drag and drop. Uninstall? Drag and drop. (there are underlying issues with files that do actually get left behind ... but it's pretty arbitrary) Rarely will you find an app that has to write files all over the place or update system files like Windows.
2. Security model. Again, no system file modification. And unlike upcoming Vista (I'm running RC2 on one of my windows boxes) you're not hit over the head 80 times to run one program. (no security is perfect, but nobody's really trying to hack mac yet).
3. Minimalistic OS structure. There's no 5-6 tiered menu structures like Windows. I don't have to go tools - options - blah blah settings - setup - yadda yadda. It's always app - preferences.
4. I just get more done quicker on a Mac. Expose and drag and drop for most functions, gets me what I want 98% of the time. I plugged in a two button mouse for right clicking, and I've since ditched it. No need to right click.
The real sticker for you though will probably be blackberry support. Entourage for Mac is pretty half baked compared to Outlook if you use an exchange server. It's redundant for everything else (pop3/imap) since Mail is easier to use. What OS X really needs is big enough market share that companies have to start developing their software for both windows and OS X. Hate to think what it'll do to the software industry's economics though.