Is Taxi expensive in Tokyo? Should I use public transportation?

Tokyo, next month, finally. It really took me some time to get around 1000e for a plane ticket to Japan. But, the good thing, or better to say, the best thing is the fact that I am not paying for the stay. I will be at my friend's place, so I will be needing money only for fun. I have intended to buy Playstation 3 there (around 600e) so I will not have much more money left. Is Taxi expensive in Tokyo? Should I use public transportation?

Always public transportation. Not only that it is cheaper, but the buses and train always come at the time written on the board. They are almost in a second accurate! I have heard of a story that few years ago, CEO of Tokyo Railways (perhaps it was some other town, I am not that sure) committed suicide because all the trains were late 30 minutes in that year! Anyway, I do hope you will have a great time there; I am still gathering money for the ticket.