Given your situation, I would recommend starting with a Superzoom as a learning phase. You'll gain a lot of experience, take some good pictures along the way, and in a couple of years, be ready to decide on your next move. Jumping into an elaborate DSLR system is expensive, and I think, risky.
With regard to "superzoom" cameras, I'd advise not going for the largest zoom ratio. and not trying for the highest pixel count. I'm not intimately familiar with the Nikon P90, so I can't advise you there. Take a good long look at the group review here on DPReview of the Superzoom cameras. They provide opinions, test results, comments on each model, sample pictures, and some general comments on the type.
I have personally owned the Canon S3IS and S5IS, and the Panasonic FZ28 and have just recently decided to get rid of the FZ28 and go back to the S5IS. The S5IS is "only" 12x, and "only" 8 MP; but it did very well for me on a trip to the Galapagos Islands last year. The FZ28 is 18x, the S5IS is 12x, but at the longest focal length they are not that much different in focal length. We all talk about focal lengths on digital cameras in terms of the equivalent 35 mm film camera lenses. So the FZ28 is equivalent to a 27-486 mm lens, and the S5IS is equivalent to a 36 to 432 mm lens. The FZ28 is only 12.5% longer than the S5IS, but the zoom ratio is 50% larger. 12.5% is barely noticeable in prints or on screen. Remember, for wildlife, it's the longest focal length that counts, not the zoom ratio. The Canon SX10IS has a 20x ratio and goes to an equivalent 560 mm, 30% longer than the S5IS, and that would be noticeable, but not dramatically so.
I do sometimes use a 1.54x tele extender on my S5IS, and that takes me to an equivalent 665 mm with very good quality.
I would not consider buying the newest models until the reviews on them are out. Newer is not always better and the camera companies are pushing the limits on lens design and MP to get better numbers for their specifications. Sometimes, they push too far.
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Jerry