Apprentice is a free program with all the cards and online support. It isn't pretty, but it works.
IRL, have a look for any game shops. They quite often have tables set up where people can play, and it's a great way of getting to know people. The pre-built decks you can buy is a good way of getting familiar with the game on a basic level, though eventually you'll want to make your own decks. It's pretty tricky at the start since you won't have a lot of cards, and in software there'll just be too many cards to get any real oversight. I think Wizards release boxes named "Deck Builders Toolset", they're a good way of getting started with building your own decks.
The key to getting started is finding people you want to play with though, or at least people who are willing to give you hints at improving your game. In my experience any Magic community will be full of such people, the problem is just finding them
Edit: Also what the person above said. FNM is a great way of getting in touch with players, and an excellent way to have a look before you invest too much money in the game.