|"I can still use Windows XP but Microsoft will not provide me with any security if I would get a virus on Windows XP.|
What can I do after 2012 to still protect myself from viruses besides buying a new computer? "
Actually, they wouldn't provide you with anything whether or not you got a virus.
The time to protect a machine is before a virus is able to infect. There's many (free) anti-virus that still work with XP (and will likely continue to do so for quite a while after 2012). Avast! and AVG tend to rank at the top, but there are others that still protect quite well. Keep your machine updated with the latest anti-virus definitions and use anti-malware software as well. Malwarebytes is generally considered the best freebie, but there are others as well.
One thing you may want to consider is updating to SP3---but having had some of my own horror-stories with that update, I've stuck with SP2 and had no problems myself.
Start using some other internet browser other than IE. Newer versions aren't being developed for XP, but the latest versions of Mozilla Firefox, Google Chrome and others are still XP-friendly (as you already know).
"Is Apple the best choice. I read that it is according to Consumer Reports. Actually they were the only computers that were ranked the best in Consumer Reports 2012."
Never having used them, I can't say; but from what I've read, they are quite adequate (I don't play the MS is <> Apple game). Realize, however, that some (or maybe even all) of your software may not work with an Apple (at least not without some serious "tweaking"). That alone could be a significant cost.
All in all, if you're daily computer use only includes surfing the internet, sending/receiving a few e-mails and playing a few "low-tech" games, I'd personally be hard-pressed to justify a lot of money for a new machine when what you have should still work fine for quite some time...
"Channeling the spirit of jboy..."