Buying my first 125cc?

I rode a 125 off road dirt bike and I loved it! But on the streets? I'd want more power... Maybe a 500 or 750. (Also, for giggles look into a Suzuki RE-5) I am 19 years old. I have gotten stupid before in a car (never wrecked one though), and I've never wrecked a motorcycle after the first time a mini bike slid out from under me when I was about 7 (I rode away from that too). I consider myself a careful rider, but I think it's much better to have a metal cage around you (like in a car) unless you are very experienced on two wheels. Remember, on a motorcycle good front brakes (no "stoppies" or "endos" here people) and a little bit of rear brake applied (once again, with the rear wheel on the ground) in a straight line will save you before 200 horsepower ever will. But power is important as well in city or highway driving. Tires are ultimately your insurance on a motorcycle though... They give you your control. Get the best tires for all around grip (may take you your whole life). Never ride the oil slick, nor the tire trench in the rain (that's where the oil goes when it rolls off of the slick crown) and always brake in a straight line. Also, at high speeds, it's lean, not turn. Watch out for manhole covers. If you plan to race, my uncle always told me "The fast guys were always crashing... If you want to go fast and you never push the bike just past it's limit, you will never win... If you were fast but you didn't crash at least once every practice, you weren't riding hard enough." BMW's are nice.