I have been teaching myself for a year, I will be taking up regular lessons starting next week as I feel that I have got as far as I can go without making mistakes and learning bad habits. I have tried books but I find them difficult to follow and motivation to stick to them is hard. The most successful way I have found is by using a midi based computer program and a midi keyboard.
I use a program called Teach Me Piano by a company called Voyetra. It runs in Windows XP fine, but it is about 8 or so years old I think. So it has to run in 640x480 compatibility mode (think BIG BLOCKY FONTS!) Because it's midi based it tells you when you hit the wrong notes on a piece, and you can run a metronome while you play and it will tell you how accurate you are at timing too.
It's not a substitute for a good teacher - but it will give you all the basics and probably set you up to teach yourself if you are intent on doing it that way.
I thoroughly recommend it.
Good luck!