Ok, I might as well give my two cents on this.
I have alot of PC experiense, and a about 1,5 years experiense with a mac. *One of the older Imac's.*
Now, mac in the 90's generaly had many, many overpriced products and they mainly focused on the artist market. However, since the first Ipod they have focused more on the mainstream market and have moved from over-priced to nice price. They have focused more on the overall user experiense which features small to big improvements in every upgrade. Its generaly stable, it does not have much of an 'computer gets old' factor and for people new to computers, its now generaly a nice buy.
The pc is a bit more of a powerhorse and for a renderer/strong software user like me, *Adobe and Autodesk software among other things* That's generaly a good thing. It features top of the line hardware which at most times does surpass the mac and it can also overclock which actualy is a big deal when you want to get your rendertime shorter. Its system is open so you can improve some settings, but you can easily do something subconsiusly that can ruin the overall experiense. Now there is no doubt that Vista is too big, but I have used it for about two years and my computer has been powerful enough to deal with it. I am not one of those people who have a ram value of 512mb and thinks its going to be a breeze. I do know however that Vienna has been told to take about 45 megabye of storage space and even uses even less than 45mb of ram which sounds insane. So I do look foreward to Vienna which is a new codeing which would imply that viruses are a no-show in its early days. Its rumored to be released early 2010.
I would call myself a pc user, I sadly have no Linux experiense yet so I cannot really comment on that. However the mac has had a wast improvement over the recent years and they got one of the coolest, if not the coolest mobile phone on the market. Design wise I actualy like some pc's more, because I know where to look and its not too hard to make a nice looking pc, but at most times I don't really care. The mac's are solid design wise and they don't have neon lights that burn your eyes out....... However I do like some neon lights >.>
And yeah, I used Tiger most of my time with the mac, but I have tried Leopard and it seems cool enough, but I don't jump up and down regarding OSX or Vista/XP. Software look-wise I could make my computer look like OSX since there is a skin like that available. However I am not too found of the steel and generaly enjoy the aero look more, but that's just me.
So if you know how to handle your pc, you can probably find a better deal. I personaly like to build my computers and I need the extra power, although I won't throw my money wildly at anything until 2010 because then things will be more clear. However if you are new to computers, you might want to check out the mac. I'd try to test before buying though.
Oh, and I need to add.
Videogames, videogames, videogames, videogames games games!