I personally own both mac and PC computers.
The "advantages" of the mac are as follows:
Fewer choices mean simpler options. When it comes to software, peripherals, there are fewer choices with a mac and so it is less likely that adding something is going to create a conflict with something else.
iLife is fantastic for processing digital pictures, editing digital movies, and working with and managing your digital music library. It still amazes me how effectively Apple has executed on Steve Jobs vision of the computer as the digital hub enhancing and integrating all these digital devices that have become part of our lives (digital cameras, digital music players, digital video cameras).
Much fewer spyware and virus problems. Because macs are a minority platform the bad guys who make spyware and viruses typically leave them alone. I mean if you are someone bent on creating digital havoc, why waste your time creating and unleashing something a platform that composes less than 20% of all computers. I am continually shocked at how many PCs that I use at my friends how are loaded down with spyware and viruses greatly decreasing their performance. Also out of the box the Mac OS security tends to be better than windows.
They sure look cool! I don't think I can come up with a company that has a better sense of design than Apple. Not just in the computer industry but in any industry. Apple products looks cool and they make you feel cool for owning them.
As far as the disadvantages:
Hard core business users in the corporate world are going to still have difficulty integrating a mac with co-workers on the PC platform. If you use MS Project or some other business software that is not included in the Office suite, you may find that it is not available for the mac. That means you have to run the mac in PC emulation mode and lose some performance.
Few choices may like life simpler but if you are really into having alot of choices you will find that you have fewer options for the mac and invariably those options are more expensive. For power users, the PC still offers a greater variety of choices and a better value for you dollar.
Web experience may be decreased. Many media intensive websites do not work 100% correctly on the mac browsers. This can be a bummer when one of your PC friends sends you a link to the latest cool website and you go there only to find that most of the bells and whistles don't work on your mac.
The bottom line:
For home users and small business owners macs are great. The integration and ease of use of the iLife programs brings alot of fantastic media functionality to the fingertips of users who would be lost trying to do the same things on a PC. Using digital photography, editing your own movies and DVDs together and managing your music library are all homeruns on the mac. Plus the reduced virus and spyware risk means that your computer will be operating on all its cylinders more often than if you had a PC.
If you are a hardcore corporate business user who does alot of financial or project management oriented work, a PC is still your best bet. Also if you are a hardcore gamer, you will be disappointed with the availability of titles for the mac.
Hope this helps!
God Bless,
Evan