Speaking from personal experience here so the advice may differ from what the others have given:
I own a ultra-zoom type prosumer and it served me well for 3 years for landscape (28mm in 35mm equivalent), macro (can focus as close as up to 1cm), and times when you need the extra reach (500mm in 35mm equivalent). All these at a relative low cost of $800 in one body. Try buying ($$$) and bringing the various lenses for these with you on trips (weight). Plus I didn't need a dry cabinet.
Even now after caving in to buy my first dslr, I am keeping the prosumer around while I play with the kit lens, and slowly save to get the lenses I want.
In short, if you know specifically what type of photography you wish to venture into, then invest in a dslr system right away. Otherwise a prosumer will give you the leeway to explore different genres without breaking the bank. And on the topic of prosumers, other than Canon Powershot G-series, there's Nikon P series, Panasonic LX series, Sony H-series, Fujifilm S series, and Olympus SP series that you can check out...