Completely wrong? Not at all! :-D But then I love small computers. I still mourn for my beloved little 12" powerbook which was one of my all time favorite laptops--and has done its best for two other people since I bought my new 13", both of whom adored that little laptop almost as much as I did.
Look, the 13" has a full keyboard and a great screen. It has all you want, is a pound lighter than the 15" and will fit on small desks. BUT, in the end, the lesson of Macs as compared to PC's is to always get what you're going to love. Given what you want to do, both computers will suffice in power, etc. But to some the 13" is too small and they love that extra bit of screen real estate. Meanwhile, to others like me, smaller and lighter is preferable. We can tell you our personal preferences from dawn till dusk, but in the end YOU need to play on both computers. There is no way for you to really decide this until you do.
I promise that if you play on both, that's when you'll know. You'll look at the 13" and say, "Hey, that's not too small. In fact it's perfect!" and nothing larger will be needed; or you'll look at the 15" and say, "I want!" and nothing less will do.
Macs are computer that you fall in love with. So pick the one that speaks to you. Because the last thing you want is to feel regret or remorse that you didn't get the one you really wanted. Take all the advice you're gotten here, keep it in the back of your mind--but decide only after you've gone into a store and had your hands on both--looked at them, lifted them, played with them.
Best of luck in your choice, and welcome to the World o' Mac!
