*. Longer usable life (3-5 years in general)
*. Higher resale value
*. Lower cost of ownership.
*. Doesnt get slow much after a long time of use (windows get super slow after a few months and requires tweaks, defrag, reformat, etc.)
*. You can install tons of apps and it won't slow down the computer (Windows have registery issues)
*. Can open multiple apps and multiple large documents and switch between the apps and documents without slow down to a crawl. (Windows have virtual memory swap file issues)
*. Does not need to pay $$ to buy anti-virus and anti-spyware
*. Processor can run at full speed (as oppose to windows machines running anti-virus and anti-spyware which slows downs windows by as much as 10-20%)
*. No pre-installed crapplets
*. comes with iLife and other software you can actually figure out without manual; you can make amazing stuff
*. Quieter.
*. No multiple vents and various protrusions on the bottom of laptop
*. Comes with remote, web cam, microphone, optical audio input/output, bluetooth, wireless-n, gigabit ethernet, firewire, DVI, etc.
*. Smaller, lighter power supply, better cord management, overall more compact and lighter. Faster to pack and unpack.
*. Balanced weight distribution (very useful if you are walking around with it on one hand.
*. Long battery life due to more efficient power management of OSX
*. Actually goes to sleep/ hibernate when you close the lid
*. Easy to connect to secure and open wireless networks of your choice (1 click!)
*. Doesn't sound like a fisher price toy for 2 year old
*. No need to click "Start" to shut down your computer
*. Girls love macs (and owners of macs)
Also,
http://www.apple.com/getamac/