No no no no no! And more no!
I used that 50-500mm F4-6.3 EX "Bigma" lens early on with a D80. It was effectively a good 50-300mm, anywhere beyond 400mm, it became soft and vignetting was very obvious - even on a D80.
I also had severe problems with the external paint-finish peeling away rapidly, despite best of care. I was then stuck with the run-around from the local distributor. The lens was just outside of its warranty period - and I demanded in no uncertain terms that the lens barrel be fixed at no cost to me - because I was aware that it was an issue affecting multiple Sigma lenses at the time. A lot of my endless following up with them (it took months of frustration), it finally was fixed - and on the day it came back, I traded it in on a 24-70 F/2.8G Nikkor.
I'd recommend Nikon's 80-400mm VR Zoom-Nikkor over the Sigma, provided you use it on D80/D90 or better type cameras.