There is nothing any computer can do that the other can't..
Linux is a great solution. It is free, easy to download and install. I would dual boot with windows. http://www.howtogeek.com/howto/windows-vista/use-ubuntu-live-cd-to-backup-files-from-your-dead-windows-computer/ (Shows how to download Ubuntu and run as a live CD)
http://apcmag.com/how_to_dual_boot_windows_xp_and_linux_xp_installed_first.htm (Shows how to make a dual boot with any windows operating system pre-installed)
Contrary to belief, Macs are not better quality. They use a lot of the same parts as PCs. Apple also has been changing suppliers to try to "lower the price" and thus lowering quality. Even with the lower prices, Macs still cost more, they spend a higher percent of budget trying to make it look pretty, and marketing.
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
WINDOWS ADVANTAGES:
Aprox 90% of the market is Windows. Most PCs include windows already pre-installed.
1) There are a number of websites that 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) If you like the Dock on OS X (Mac) google/yahoo rocketdock, objectdoc.
I Would also install Avira AntiVir, Avast, Comodo Firewall on the Vista since there are free versions.
LINUX ADVANTAGES:
1) Install Linux, and then get tons of stuff for free. Updates done, etc.. Linux is very easy and has tons of software that will be updated automatically. (Checking a checkbox in either two ways to install (Add/Remove or Synaptic Package Manager), search for something I want, check a box and click apply)
2) If you like the effects on a Macintosh go yahoo or google COMPIZ FUSION. It can do just about any cool effect a Mac can do and more...
3) If you like the Dock on OS X (Mac) google/yahoo Cairo Dock, avant window navigator.
4) Linux is MORE SECURE. I surf the internet and can even run some windows programs on Linux.
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.
All you have to do is..
A) to download .iso file off the internet from the Linux website
B) burn the .iso file to a CD or DVD (Make sure your burning software can burn an ISO)
C) restart the computer with the CD in the drive
D) As computer is restarting, press on F12 Key a bunch of times to get a boot menu
E) Select the option to boot from CD or DVD.
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
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.
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".
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.
Macintosh's are far from bug free. 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.
http://www.tuaw.com/2008/08/01/apples-quality-dwindling-my-macbook-pro-sob-story/
http://news.softpedia.com/news/Microsoft-Finds-Irony-in-Mac-OS-X-Getting-Hacked-Before-Vista-SP1-82135.shtml
http://www.ubuntu.com/
http://www.kubuntu.org/
http://www.freespire.org/
http://www.pclinuxos.com/
http://distrowatch.com/
http://polishlinux.org/
http://www.desktoplinux.com/
http://xwinman.org/gnome.php
http://xwinman.org/kde.php
http://www.linuxalt.com/
http://screencasts.ubuntu.com/
http://www.linuxfoundation.org/en/OpenPrinting/
http://www.avast.com/
http://www.free-av.com/
http://www.personalfirewall.comodo.com/
https://help.ubuntu.com/community/SwitchingToUbuntu/FromMacOSX
https://help.ubuntu.com/community/SwitchingToUbuntu/FromWindows
Google/Yahoo OS X on PC