15" i5 or i7?

I am about to buy a 15" Macbook Pro, I have been wanting it for sometime but my only question is should I get the i5 or i7. I will not be upgrading anytime soon, money is not really an issue but what are the pro's and cons? Does the i7 produce alot more heat? Does it kill the battery alot faster? How much % performance increase is it?