First Car. Infiniti G35 Or Ford Mustang.?

Well, i'm going to purchase my first car (USED) this weekend. I have been driving for 6 months or so (I'm 19), and going to purchase my car this weekend to have for the winter, for school and work. I was thinking about buying a infiniti G35 then talked to my friend about the new Mustang Gt models. I'm torn between the two. I'm looking around the 2003-2006 G35's and the 2003-2008 Gt's. I 'm wondering what's the best for me. In terms of price, insurance, performance and jsut wondering which one whips in more horsepower at the end of the day. Help please. Tell me your opinion.