I agree with everyone else above. I used to play using play money too, until I made my first deposit. Things are so different.
I used to play at a bar and the guy who worked there used to play using play money too at Stars. Now that I started playing for real and trying to get rid of some habits. Sometimes he passes by my table and looks at the my folded hand and says "Oh my God, how can you fold A9o?" and that drops my mouth wide open.
Play money, you don't consider position, number of oponents, pot odds
, antes, etc. You just look at your hand and ask "Can I win?", and you play it. There's nothing else to take into account. So what if someone re-raises a raise pre-flop? You can still call with JT and hope to catch a straight. Go thinking like that into real money and you are doomed.
Spending money on play chips does nothing to help you, and everything to help PokerStars
: not only do they profit directly from the purchase, more play chips will only get you more into poker or into thinking you are good at it, and eventually you'll get into cash games and give them rake.