the D300S is a D300 with video ... not exactly what i would call a new model (though my aunt in toronto just bought that model)
the D90 is a dinosaur
(a new model should be imminent, though i don't really watch the timelines of the nikon models) the canon xxxD's are 1 year, xxD's are 1.5 years, xD's are 3 years or more
though i was talking about the D90 when i said $ for $ the better body.
check the prices for:
17-55mm Canon and Nikon (20% more)
24-70mm Canon and Nikon (30% more)
Nikon = more expensive lenses ... at least this time, camera prices are cheaper over here than in North America
the D90 ISO performance is overhyped (my brother has one) it's basically the same as the Canon xxD ISO performance though definitely useable over the lower models' ISO performance.
i've never used more than 3200 on my 5D, and that's the ISO king on the market (save for the crazy night vision 1D and Nikon Dx's)
what i'm learning right now: best upgrade in camera systems ... tripod and lighting.