If you have existing lenses that would work with a new digital Nikon and if they are of focal lengths that you can use I would say stick with them. But ... if you are going to be buying into a new system please check out the other brands.
I'm the owner of an Olympus UZ-700 and an UZ-725 I also have a Nikon CoolPix 5000 and a Sony video camera. Brand loyalty does not drive me in my purchases. I buy what works best for me. When it was time for a DSLR, I studied the situation for several months then bought into the Canon system.
Being the owner of a SLR system already, you know that deciding what brand of body to use is a big decision that controls other decisions, especially your lens purchases. The lenses are going to cost more and last longer than any digital body. One indicator of a product's value is what it is worth on the used market - just look at the resale value of used Canon EOS lenses. They hold their value to an amazing degree. That told me almost everything I needed to know.
But, if you don't ever plan to expand your photography (ie purchase additional lenses for landscape, telephoto, portrait or macro) don't worry too much about which system. Just price out (for each brand) the costs for body and lenses that you know you need then buy what is less expensive and gets the job done.
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