+1 to what poopers has said above.
Canon have just released the 5D MkIII so the previous mark 2 and even the mark 1 models are cheaper than ever. Because these camera's use a full frame sensor ( one that's the same size as a 35mm negative as opposed to a normal APSC sized sensor which is about two thirds that size ) you can shoot in dimmer conditions. That said if you can't afford a decent lens to go with it the FF sensor will really show it up. Depends if you can make money from photography or have just won the lottery if you want to splash out on a really good camera.
However... In today's market of constant tech and everything else almost any DSLR will be very good, the lenses are what really make the picture ( and the photographer obviously
).
If you've got about a grand spare the Nikon D7000 is a cracking piece of kit !