Glenn: no, all of the cameras you provided links to above are "bridge" cameras, some with longer zooms than others, but all having fixed lenses that cannot be removed from the camera. In order to have any sort of flexibility with regard to being able to change lenses you will need to go with a DSLR. The DSLR comes from the heritage of Single Lens Reflex cameras, which had interchangeable lenses. At one time there were also rangefinder cameras which had interchangeable lenses as well. There is a lot of benefit to having the abiility to swap out lenses, but, yes, there is a higher cost to be paid than if someone buys one of the all-in-one fixed-lens bridge cameras.
For those DSLR buyers who want a fairly long lens range without needing to swap out lenses frequently, there is Nikon's new 18-200 VR, which I suspect will live on many people's DSLRs and never be removed. (For samples from that lens have a look at the "Signs of Spring" thread in the picture gallery.) I love that lens, but it's not my only lens. Today, for instance, I shot the images seen in that thread, then came in the house and swapped lenses, putting on the 105mm macro lens, and went back outdoors for a go at the daffodils. (I'm not too pleased with the results so you aren't seeing those!) Tomorrow, I'll tackle the project again, having seen where I could have done better. Today was rather windy, which made it difficult, too, as I had to have a higher ISO, wider aperture and higher shutter speed than I really wanted so I wasn't able to get exactly the look I was after. I also really should have been using a tripod and I hadn't bothered...
Anyway, IMHO you could do very well with an investment in a reasonably-priced DSLR body and the 18-200 VR lens, also adding in for not that much money, a 50mm f/1.4 or f/1.8 for shooting in ambient low light. I don't believe that you can put a TC (teleconverter) on the 18-200; that usually is reserved for lenses such as the 70-200 and the long prime lenses. The reasonably-priced 70-300 mm lens gives a bit more reach than the 18-200 VR, so that's another possibility, and in that instance you could use the kit lens which is available for the D50 or the D70, the latter being considered a better one. That particular combination of three lenses (18-55 or 18-70, 70-300 and 50 f/1.4 or f/1.8) would get you off to a good start. The 70300 can also accept teleconverters, which would give you additional length and range, but you do lose something in the amount of light coming into the lens.
Anyway, of course it's your money and your decision, but I suspect that you'd learn much more from working with a DSLR than with a fixed-lens all-in-one bridge camera. JMHO....
Have you read reviews on any of the cameras referenced in those links? That's obviously very important, too, as each will have its pros and cons. Also check out the forums on DPreview and Fred Miranda for those specific cameras, too.
Good luck with this decision!
