As far as performance goes, the Apple stuff is fine, but nothing special--definitely not for the cost!
With all this talk of OS X feeling faster than XYZ PC, what was that PC?
I can walk into Fry's (well, if I happen to be on the way to Atlanta), use a demo OEM rig with killer specs...P4E 3.2, 1GB RAM, 6600GT...and the damn thing feels like a snail compared to my 1800+. If any comparisons about multitasking and responsiveness are to be made, they should be from a standpoint of having a fresh OS w/ AV software. Big OEMs (Dell, HP, former IBM, Gateway, etc, not Falcon NW, Alienware, etc.) don't know how to make a home PC that can start Firefox in a second or less.
In fact, the worst I've yet seen was my doctor's 3200+. 1GB PC3200, so-so- video card, nice big fast HDD. Just getting a context menu on a file on the desktop took half a second.
As for the rest, it is all preference. I don't find my Windows PC to have an ugly look or feel...OTOH, if I'm not developing a theme, I'll have xoblite with LS on top and BBLean's window skinning (xoblite takes over the desktop mouse actions, though). That brushed OS X look ain't got nothin' on a beveled, raised diagonal gradient purple to black titlebar and beveled flat silver bottom grips

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I dislike the look and feel of OSX and whatever Apple wants to call their desktop environment. OTOH, I also dislike Explorer, and to a lesser extent, KDE and Gnome (partly because they are both like Explorer with extensibility), so I'm an equal opportunity lowest common denominator desktop environment hater

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On real performance, benchmarks are not crap, but only need to be within a margin of error. So what if the Windows version of an app runs 20% faster, if your guys use OS X day and day out, not Win2K/XP? That 20% would be eaten by working with something unfamiliar, regardless of which is superior (or not, as we could argue about that for days--then months after open source options are mixed in). When you get into 100% or so differences, or the machine needs to be a workhorse, then you might look at changing tech.
When it comes to stability, the app makes the difference. The last time Windows 2000 crashed on me, I gave it the wrong network driver, and told it to use it anyway. Silly windows, it's not idiot-proof!