To everybody "afraid to die" :
"If you're not busy living, all you're doing is dieing"

For a first bike, there's no such thing as a bike "too small". All you guys talking about not buying anything under a 600cc sport bike, and being "bored" in two weeks sicken me. The point of having the extra power is to use it wisely. If you're starting out, the deck is stacked against you in that area.

A little ninja 250 is a great bike to start on. It's small, light weight, and fast enough to not get run over trying to merge on the interstate. That said, it's not powerful. The point of a starter bike is to have a mechanical limit to your testosterone driven invincibility complex. You can wring the neck of a 250, and not get in any real trouble. If you start getting comfortable on a 600 and decide that you're "good" enough to push the limits a little harder, the pavement will correct your misguided attitude.

My suggestion is that if you have very limited street riding experience and little to no dirt experience, start small. 600cc is not small, if you grew up with an 80cc thumper between your legs on an open field and moved up from there, then you know what I'm getting at. If you're serious about riding, you won't care that you're limited to 250cc for 6-8 months, you'll still grin big just being on two wheels. If you ever get to the point where you see the little 250 as a chore, then riding anything bigger is not for you. Riding a fast bike is a thrill, but that shouldn't be the reason for riding. Riding for a thrill is keeping the skin-graft medical branches alive with your insurance dollars and unemployment.

The bottom line is that for your first bike, you're going to take everything I've just said, dismiss it, and buy what you want anyways. Just remember these few things:

and lastly