Personally, I would start with a used 500. It's cheaper and will give you an idea what kind of bike you like. The Ninja 500 is well regarded and I don't think getting your first bike is a time to let your ego get in the way. Used bikes seem to hold their price pretty well so getting rid of a 500 or 600 for that matter shouldn't be hard if you set your sites on another bike in the future. When I started back in the neolithic age I only had an 80CC and a 350 was considered big. I now ride a Honda VFR 800 CC but it's probably not as fast as most 600s. Some think it's a good idea to start on a standard bike because you won't be damaging bodywork. Here's a site where you can get some advice and other info. Have fun and take a riding course. Sign up now for spring as they get filled and don't forget to have some money for a helmet, jacket, gloves and boots.
http://www.cmgonline.com/
Safety course at
http://www.calgarysafetycouncil.com/
Hope this helps.