Today, Macs use the same hardware as PCs. Why spend extra to get the same CPU chips, graphics cards and OS X isn't as secure as you think.. Look below.

WINDOWS ADVANTAGES:

Aprox 90% of the market is Windows. Most PCs include windows already pre-installed.
1) A number of websites still require Internet Explorer to view and IE for Mac Stinks (it is really ies4osx which is the Windows IE version running really buggy on OS X and illegal if you don't have a legitimate copy of Windows, too many problems with it).
2) More supported peripherals (printers and other things you hook into the computer) on Windows.
4) Like the Dock on OS X (Mac)? google/yahoo rocketdock, objectdoc.

Install at least Free Versions of Avira AntiVir, Avast, Comodo Firewall on the Vista.

LINUX ADVANTAGES:

1) Install Linux, and then get tons of software for free.Update software easily and automatically. (Checking a checkbox in either two ways to install (Add/Remove or Synaptic Package Manager), search for something you want, check a box and click apply)
2) Like the Mac OS X effects? go yahoo/google COMPIZ FUSION. It can do just about any cool effect a Mac can do and more...
3) Like the Mac OS X Doc? google/yahoo Cairo Dock, avant window navigator.
4) It is faster/MORE SECURE. Surf the internet and even run some windows programs with Wnehq/Crossover..

LINUX OS
If you are worried about viruses, spyware, security, Try Linux (it is free), I have included some information about Linux and links so you are not lost if you decide to try it.

Easily turn your system into a Dual booting computer with Linux, fast, safe and secure, easy to use (contrary to belief). You then get the best of both worlds (Windows with all of its supported products, freely go online without the worry)

My Recommendation would be either Ubuntu (Most popular and well supported linux), Kubuntu (KDE version of Ubuntu),
Freespire (has all windows codecs for watching videos, dvds out of the box),
PCLINUXOS (very nice Linux, easy to use and polished),
There are so many good versions of linux besides these.

PLEASE NOTE: In linux there are many forms of Windows Environments, the two main ones are KDE (K Desktop) and GNOME. Ubuntu uses GNOME, KUBUNTU is a KDE version of Ubuntu, PCLINUXOS, Freespire use KDE... The differences in the window environments (DESKTOPS) control how you configure, open close the windows, the appearances of the windows... linuxfoundation.org/en/OpenPrinting helps with printer support. ScreenCasts.ubuntu.com shows video and non-video help with learning to work with Ubuntu.

There are many good Linux distributions for different reasons, distrowatch.com, polishlinux.org, desktoplinux.com are good websites for overall understanding linux.

Installing Linux in general is very simple and much more secure than OS X(Macintosh) and free.
Also, most Linux distributions have a LiveCD which means you can try without installing...
UBUNTU, KUBUNTU, FREESPIRE, PCLINUXOS, etc.. all have live CDS.


ANOTHER QUICK NOTE: People have been able to run OS X on a PC since the PC and Mac use the same hardware. This is not legal and I would not recommend it for security and legal reasons, the purpose is to show that there is nothing special about the MAC.

A)Price...
A similar equipped PC is much cheaper to purchase than Mac

) SECURITY:

Mac OS X was hacked in 2006 under 30 minutes, and hacked within 2 minutes in a contest in 2008. Linux and Vista were not able to be hacked until another day when restrictions were lowered.
All macs are standardized with Cameras, if your system gets hacked, the hacker would more likely be able to turn on your camera.
Please Note: All OS's have vulnerabilities.

C) VIRUSES

The argument that OS X has less viruses is true, but that is against XP, BUT Mac OS X has viruses, a friend of mine has a virused Mac. As more users use Macs, more viruses will come out for it. Especially when users think "they are safe".

Google/Yahoo Mac Viruses


D) WINDOWS LICENSE is discounted with PCs

You do not pay the full price, for instance Dell -> you pay $50 or less for Vista Home Premium If you buy a Mac and want Vista, you pay full price.


D) EXPANDABILITY & REPAIR...

Repairs are more expensive than PCs since the IMac, Mac Mini are compact units, and Apple charges a premium for their services. Some repairs can be done by another repair service but the compact design of the computer causes problems.
With an IMac, if the problem is with the monitor, the whole computer would have to be brought in.
IMac and Mac mini lack expansion.


E) PROBLEMS

Sample of problems: Overheating Macbooks, OS X- not responding to keyboard, some units with 16bit screens, etc. Apple statistics are misleading since Mac users with problem machines are more likely to go out and buy a new computer than PC users. Apple is lowering prices which means you can expect lower quality than in the past. Apple had switched the manufacturers producing parts. OS X also has problems slowing down.

Moral of the story : Apple still sucks :P