I'm no pro photographer, but I follow the SLR market quite a bit.
Personally, I don't like Pentax, Olympus, Samsung, Panasonic or Sony that much. I like them, but I wouldn't necessarily recommend them to a beginner. Olympus, for example has some fantastic zoom lenses - but the Four Thirds system has some drawbacks (what Dorian Gray said).
Anyway it's a tough decision. Sony's cameras have really great bang for buck, but the Sony lens system (not including Minolta lenses) is underdeveloped and expensive. Sony's cameras also suffer from worse high ISO noise performance compared to Canon and Nikon.
Nikon's D40/D40x/D60 are lacking some features - like being able to autofocus older lenses. But that's not really a biggie for a beginner. I would be more concerned with the lack of focus points.
Canon's offerings seem to be good value for money, but I don't personally love Canon's ergonomics. They are a bit pricier than the others too in my experience.
Nikon and Canon have the widest, largest, most expansive lens systems - but there's some real junk in there (especially on Canon's part
).
Of course, they're all good. I'll echo the idea of going and trying them.
