Tooo much talk of Vistaaaa.... Apple fanboyism taking ovver....
If you want a desktop, just get an Apple iMac. You get a stylish, silent, small (its an all in one machine), power efficient computer (power consumption is under 180 watts under full load for the top 24 inch model) that is fully pre-assembled right out the box. All you need is to hookup the power cable and keyboard to the back of the machine and then plug the mouse to the keyboard (built-in usb hub), connect to your wireless network and you are all set.
If you don't want OS X, no problem, run Boot Camp and pop in a 32bit CD/DVD or XP/Vista, install it and run Windows natively. Then you can switch back and forth or remove OS X completely and use the HDD completely for Windows (but why would you want to that anyway).
The following are my opinions on the XP, Vista and OS X, pro vs. cons really:
Best things about OS X:
1. NO VIRUSES, NO SPYWARE, NO CRAPWARE PREINSTALLED, no need for antivirus software.
2. Simple UI, simple drag and drop installation of Applications, no hunting for drivers. Great built-in apps; Mail, Calendar, Quicklook, Spaces, Exposé, Dashboard, Photo Booth, Spotlight, I could go on and on...
3. Its Unix underneath. (see #1) More stable, full 64 bit OS, with a mayor OS update on a practically yearly basis (paid upgrades though).
4. No confusing multiple editions of the OS, one version has it all, no Home Premium, Basic, Ultimate, etc. Oh and it retails for "only" $129, a small price when compared to the $399 price tag on Vista Ultimate.
5. Spring folders, you have to use it to appreciate it, when dragging and dropping, pausing on a folder opens that folder so its way easy to copy files in deep folders with only the mouse.
Worst things about OS X
1. Learning curve, we are teached even in gradeschool how to use computers, and 90% of them have XP. You might have a hard time at first but once you get used to OS X you will get spoiled and will never look at that beige box under your desk the same way.
2. Multi-minitor support, seriously it sucks. No support for some Windows specific files (like wma, wmv) without (mostly) free third party utilities. Mouse Right-click function disabled by default, you must enable it in the system preferences.
3. Microsoft still messes with you. Office 2008 is available for the Mac, but it is buggy and slow and very different compared to Office 2007 for Windows. Apple's iWork 08' has poor support for Office documents.
4. Its a closed system; OS X is only meant to run on Apple hardware, although its possible to run it on a normal PC, it requires the patching and hacking of the OS to work at all and its against the EUA and doesn't work too well.
I've been using Windows for years and switched like 8 months ago. I'm very happy with OS X. I work as a computer tech and using OS X has been a great learning experience as well as opened more doors as to possible clients, specially now with the higher adoption rate of OS X over Windows.
But Vista isn't all bad, I like a couple of things Vista does better than XP, some are even better than Apple's approach as well.
Best things about Vista:
1. Smarter copying of files: If a file exists with the same name, it asks you what to do, Skip, replace, or keep both. XP and OS X will just say there was an error and stop the transfer. ARRGGGG!
2. Ability to resize the OS partition non-destructively. Great for dual-booting Vista and XP with Vista pre-installed. OS X can also do this BTW although not as easy.
3. Good multi-monitor support, the same cannot be said for XP or OS X.
4. More secure than XP out of the box. IE7 a big improvement over IE6 but still less robust than Firefox or Safari.
5. Not to worry, Windows 7 is due out next year... or will it be Vista all over again and be released in 2012?
Worst things about Vista:
1. The smarter file transfers... well file transfers can/will take up to 3 times longer to finish copying compared to XP, OS X.
2. UAC is no annoying that its useless, forcing people to disable it and making things less secure by doing so. OS X has something that works like UAC but its way less intrusive, only asking for a password when writing a system file or with some updates.
3. Resource HOG, a Core 2 Duo CPU and 2gigs of ram should be the minimum requirements. Feels slow.
4. It still Windows kernel underneath. BSODs, Viruses anyone? Most of the spyware, adware and viruses that can infect XP can also infect Vista.
5. We seriously waited 5 years for it and it still needs more time it seems. Applying the Service Pack 1 had a 50% rate of crashing working computers!