I own two right now, and I can't for the life of me, see myself buying anything else. Reasons being if nothing else, the stability, I haven't had a " crash " of any sort since using a mac. Other than a bad pci card in the iBook G4. The depth of OS use is amazing, deleting something, anything is as simple as dragging it to the trash, and it's gone, thats it. The open source software is endless, you can change filet ypes to any ( at least I haven't found any extensions that i couldn't simply change ) . And security, we don't even have to go there, nothing less then trying to dig though the fort knox walls w/ nothing but your bare hands. Reasons for this are most likely, people that want or own a mac , have no need to cause trouble, and those that aren't familiar w/ unix, have no clue how to cause trouble. Don't forget about the OS itself being a brick shit house in terms.
Networking is a dream come true, yes , a few things changed in Leopard, but thats just progress. Running a windows OS either in parallels , or on another partition for gaming is a breeze as well, flawless.
I could go on about my reasons, but I'll end w/ I plan on purchasing an iMac soon, but not soon enough.
The marriage of intel and apple is the future of computing, at least for the foreseeable future.