I’m planning on buying my first SLR (a digital). I hope to learn a lot about photography in the next year and eventually specialize in doing actor headshots, dog sport photography, and pet photography.

I want to buy a relatively inexpensive camera to learn on, but also one that I will be able to use as I transition to being a professional. I’m trying to decide between the Nikon D40 and one of the Olympus cameras (E-330 or the yet-to-be-released E-510).

Here are the questions that I still want to know the answers to in order to make my decision.

Sensor dust. Is sensor dust is a big problem when changing lenses alot? Is it simply a matter of blowing the sensor with a hand blower to clean it off? Or does it eventually become a real pain to constantly be removing it with software? Is this a good enough reason to ditch the Nikon for the Olympus?

Image stabilization: For what I’m trying to do, is this important? I plan on doing most of my shooting in good light, but would like not to have to use a tripod most of the time. Is it better to have image stabilization on the camera (like with the not-yet-released Olympus E510) or in the lens (the Nikon 55-200mm)? Does Olympus have similar vibration reduction lenses?

Aspect Ratio. I’ve heard that for headshot photos a 4/3 aspect ratio works better because there’s less cropping for the actor standard 8x10. But does shooing in this aspect ratio make your photographs seem less professional than those using the old film aspect ratio?

Any comments would be greatly appreciated!