Hmmm
Okay, this really depends on what you want a computer for. If you are just doing basic "email mom and dad a few pictures" Windows and Mac should both serve you fine and you can probably get a Windows machine cheaper.
Here is the issue, in my experience (and this is my experience, everyone else's will vary) the Mac is FAR more dependable than Windows. I have two (desktop) PCs, one about 4 years old (XP, SP2, more table than the Vista machine), one practically new (my wife has software for her job that only runs on Windows) and I have 3 macs (4 but one is so old it is only for the kids). One mac (the one I am typing on) is almost 6 years old. When purchased it was top-of-the-line and it STILL runs everything I need, this includes the Adobe CS3 suite, a variety of other photo and video editing software, etc. I also have 2 laptops (3 yrs and 1 yr, the older one is used by my wife). We have had consistent problems with the PCs, including the NEW machine running VISTA (been cleaned, well, hell, LOTS of work done on that machine really). My 6 year old Mac, well, it is my workhorse machine and literally hasn't crashed a single time during 2008. I believe some MS Office programs have crashed something like 2-3 times this year, but that won't bring the whole thing down.
What are you going to do with the computer? If you want a machine for games, Windows wins hands down. no question about it at all. If you do ANYTHING with heavy graphic use of photos or video editing, well, I am sorry but the Mac kicks Windows around the block and leaves it whimpering.
If you are only dabbling and use your machine for email, appointments, a few photos here and there, and maybe some simple writing or bookkeeping then you have a different decision. Honestly, you do not NEED a powerful machine for these things, you can literally buy an old second-hand machine and find software to do all of these things fairly easily. It WILL require work on your part though. Otherwise, you need to choose between an inexpensive Windows machine or one of the cheaper Macs (still expensive, but I'll get to that).
My personal bias is that the Mac is going to have more USEFUL tools out of the box than a PC and that those tools are easier to use than those on a PC. Remember though, I am used to Macs, they are different. Once you get used to a Mac it is easy to point at laugh and the steps people go through on a PC, but if you are used to a PC, the things people do on a Mac will make you feel the same way.
So, long story longer, it boils down to taste and what you use the machine for. If you are playing games, I don't care what the Mac fans (like me) might say, you need a top of the line PC with a huge honking video card. Otherwise, the Mac is a stable robust machine that can last a very long time. In addition, the Mac comes pre-installed with software you are actually likely to use, and if you use it, it really does save money over buying equivalent software for the PC.
Let's face it, when I bought the machine I am typing on now I figured in 2 1/2 years I would need another. Right now, I can't find an excuse to buy a new desktop (even though my year-old laptop is a little faster for some things). Do you know anyone that can say that about a 6 year-old PC, even if it was top of the line when it was purchased?
I hope this confuses the issue nicely

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Patrick