Ok, so this topic gets PC folks all in a huff. But, I own numerous Macs, and I was a PC fanboy all my life up until about 5 years ago, defending PC's and saying ignorant things like "Macs suck, if they were so great then why do they only have 5% market share?" blah blah blah. Well, there are alot more Ford Focus cars than their are Ferrari's, but that doesn't make them better does it?
Ok, is there anything you cannot do on a Mac? Absolutely not, don't let anyone tell you differently. I have, on the iMac I am typing on right this second, the full install of Windows XP (Vista blows) on this very machine. Not a simulated version, but the full real deal Windows XP. You can use Boot Camp that comes installed with OSX, and run both operating systems if you want, just reboot and hold the option key to choose which OS to boot up in. Why do I have XP on my machine? One reason, the video game Asheron's Call, which was developed in part by Microsoft and only runs on Windows. I only boot up the PC side to play that game.
Now, here are some great things about the Mac, things that it does alot better than it's Windows counterpart:
iPhoto: iPhoto is an amazing program that Windows has tried to copy with Vista, but they fall way short. It's the perfect way to store & share your photos, plus you can, with the click of one button, post your photos on the web. Just find my DNA #177 thread, that was all done with iPhoto.
No viruses: Now I'm not going to say that there aren't ANY viruses with a Mac, but owning 11 Apple computers in my life, 7 of which I own currently, I have never had a virus, or heard of anyone in my industry having a virus. I also do not have any virus protection programs installed on my machine, they just don't write code for it yet. If the market share grows, maybe, but right now if you are a hacker, you want to affect the most machines you can at one time, and to do that you target Windows.
The rest of the iLife programs are really great, iMovie, Garage Band, iDVD all awesome. I am a professional video guy, so I don't use iMovie or iDVD (I use Final Cut Pro and DVD Studio Pro), but I know they are user friendly. Garage Band is awesome man, you can record a ton of tracks at one time, as long as you have a usb or firewire device that can get your guitar or anything really into your computer, you just hit the record button and your off. The iLife suite comes pre installed with each new Mac.
You also have your standard programs like Microsoft Office and the likes, Quickbooks has a Mac version, Quicken and all the standard business software everyone uses. I use Mail, Address Book & iCal instead of the Microsoft counterparts, but that's mainly because they sync so well with my iPhone.
PC's are great too, and are a little cheaper, but the price difference between the two are alot closer than they used to be. Plus, say what you want about Apple, but their stuff just looks a f*ckton better than anything on the PC side right now. I'm just talking cosmetics, it's amazing that the PC side hasn't had one company that can make a non-clunky looking PC.
Now, if you are totally into PC gaming, and that's your thing, then get a PC. I personally never cared for using a keyboard to play a game and use my XBox 360 & Wii, but if you just HAVE to play games on your PC, you can still do it with a Mac, booting up in Windows mode, but you can get a better gaming system (better video card mainly) with a PC. Yea, you can get a bad ass video card on a PowerMac, but not many home users spend $10-$14k on a machine like my company does

. I have a badass PowerMac that I edit on, and it can handle anything, but I don't get to bring it home.
Now, note that I'm saying some good stuff about PC's too, so no need to get to flaming me PC fanboys. I have noticed that those who hate Apple so much have never actually used a Mac, I know that was the case with me personally, but I guarantee you will fall in love with the OS when you spend some time on it. Just simply things like installing software is easier. Oh, and I am also a stockholder of Apple, so I am very biased there (purchased it at $35 per share).
Both are great, both will do what you want them to do, but in my opinion, the Apple is just easier to use. Flame on boys, flame on...