Hi
Thanks everyone for your advices. I'll definitely go into the store beforehand and see how every camera feels in my hands. But I'd like to stay with Nikon or Canon (if I broaden my choice to other brands, than I'll get even more confused, as I'm not enough right now).

Thanks Gregg for such a wide interpretation. From all that I have read so far, Nikon D700 seems to be my favourite (if the price wouldn't be so high I would probably go for that one straight away).
As it goes for what I like to photograph is like that. I like to take my camera everywhere I go. What means, when going to city I will take photos of architecture, city in night (this is why I would like a camera that produces (relatively) good pics at higher ISO); when going in parks (what is my favourite) I will take landscapes and of course wildlife (you wrote landscapes and wildlife are in contradiction, but from my point of view those two fields are actually very closely linked), when traveling I would take photos practically of everything, there are also family/friends gatherings, etc. Since I usually take photos outside it would be a big plus if a camera is environmentally sealed. So, generally I would probably need a good all rounder (at least for beginning) with maybe 1 or 2 lenses for beginning.
I cannot say I really know what I am doing with my camera (I am still learning), but I almost never (except in the case of sunset, and sometimes with sport) use scene modes (I usually use AV or Manual settings).
I must admit I still don't have a good understanding of lenses (can you advise me any good book or website, where I could find a good explanation). There are also many different books on SLR photography and I wouldn't like to buy just one, can you advise me a good book.
Cheers.
Sandra