Susan:
Here's what I think about people knowing nothing about computers teaching people about computers:
OK, despite my rant about not wanting to fix your computer, I am very happy to post a few things about computer selection.
First of all, yes, I have a bias toward Mac for most users, simply because what it does, it does right and what it doesn't do, it won't do at all. If you get a used mac, get a "G4" system at the very minimum running OS X 10.4. Better get the newer Intel chip based Macs, they are faster, better, stronger, etc.
Peripherals are simple. 90% of the time, installing a printer on a recent vintage Mac consists of plugging it in. That's it. Just plug it in, pause a moment, and print. Similarly, with digital cameras, you connect the camera, and the picture will transfer to iPhoto. The security of a mac is good, but not perfect, and yes, there are actual viruses for the mac out there. Software availability is good, Openoffice, which lets you make MS Word, Powerpoint and other "office" documents is free (
www.openoffice.org) and OK, the iWork suite (Keynote for presentations, Pages for documents and Numbers for spreadsheets and math documents) is utterly awesome but when you down-convert to other formats, such as powerpoint or MS word, you loose a lot of the nice features. Maintenance on a Mac is - usually - simple. Their laptops are good, but not that durable, you need to buy the $250 Applecare insurance, your laptop WILL break at least once in 3 years and you'll be glad you had the insurance.
That said, if you are willing to work a little bit harder to get stuff connected (printers, scanners, Roku boxes, whatever), you will save a bundle of money with a simple Windows XP box, but I have never encountered an XP system used by a "novice/casual" user that didn't have spyware and viruses on it. I even almost got one the other day, but it was intercepted by Clamwin, the anti-virus I prefer.
Finally, there's the 3rd way, which is 100% free using open-source software. I think Ubuntu is the most mature and ready for primetime package, and it runs OK on older (2003 vintage) hardware. That said, there's only two use cases I see for it. Case 1: The utter novice who never does anything but use the web browser and maybe - just maybe - has a digital camera. In this case, a Ubuntu Linux with Google's Picassa package added in (relatively painless) is perfectly fine. If they want to install ANYTHING, if they want to do ANYTHING other than the web and email, they will need some "computer skills" (more coming on that).
Case 2: A geek (like me) who likes to tinker and customize ALL DAY LONG. It's a busybox for adults.
For the novice users, there's no real disadvantage compared XP. It's a lot cheaper - some say free. As far as the software being "free" - my favorite saying about Linux is "Linux is free if your time is worthless". So, if you have some time, or if you actually want to learn more about computer systems, by all means, go for the Ubuntu.
Now, one thing that I need to pontificate on.
Computers are machines, certainly the most complex machine you'll own. More importantly, computers are machines that require their operator to observe explicit behavior of the machine and respond accordingly (there's a window that says "press any key to continue" - what do you do, what DO you do?) and also to infer what the outcome of an action will be. For example, you get one of those USB keychain drive things. You plug it into the computer. What next? Do you understand that the device will appear as a new disk on the system? On windows, at home it might show up at the "e:\" drive and at your buddies house it might show up as the "h:\" drive. On a Mac it will show up with a name, not a letter, and on Ubuntu it will show up as a named "volume" in the "filesystem".
Do you really "get" files and "folders" on a computer? No Mac or PC will help with that - that's a key requirement of the peripheral located between the chair an keyboard.
I often think that novice users should start out with a command line. No windows, no mice, no icons. Just a cold terminal window. Because that FORCES you to build a mental map of the inner workings of the machine, it FORCES you to develop an abstract level of understanding of how a file system and operating system work. More importantly, it gives you the ability to treat the organizational principles and functions of a computer as an interchangeable abstract concept.
For example, any of the geeks here would know why these command-line descriptions of certain "folders" (directories, really) are related:
/var/opt
/usr/sbin
/usr/bin
/bin/
c:/Program Files
/applications
(depending on the computer, these all represent places you'd expect to find "programs")
I'm just saying is that a Mac isn't going to make you a competent computer user, any more than a Glock 19 will make you a competent gun owner. In both cases, they are intuitive machines that have fairly obvious functions and they allow you to immediately set to using them. In both cases, you can end up with a big mess if you don't take some time to learn how to use them.
All I ask of any and every novice or "I don't really get computers" people is to spend no less than 12 hours with basic tutorials on how to use computers. I like the "for Dummies" series, but go to a book store - a real, physical book store, and look inside the books. If you see one that you like in terms of how it is laid out and how it reads, buy it. Turn off the television at night and spend the time you would have spent watching Americas Funniest Industrial Accidents or some such and use that time to enrich your computer skills. There's no downside at all to learning more.