You can take pictures with a point and shoot but they have limitations that will annoy you compared to an entry level DSLR. (D40,D60)
You can take pictures with an entry level DSLR but they have limitations that will annoy you compared to a "just not quite barely a prosumer" DSLR (D80,D90)
You can take pictures with an "just not quite barely a prosumer" DSLR but they have limitations that will annoy you compared to a prosumer level DSLR. (D100, D200, D300)
You can take pictures with prosumer DSLR but they have limitations that will annoy you compared to a professional level DSLR. (D700,D3)
(For convenience sake I'm lumping the D700 and D3 into the same bracket)
The difference between all of these is budget. We start off at anywhere around $100-200 and go zipping all the way up to several thousand. Every single one of them will take pictures, and every single one of them is capable of good pictures... but the less money you spend, the less capability you have. Period. It's literally a matter of absolute technical limitations.
The
one exception? You can't shove a DSLR into your shirt pocket.
