I agree with mv, remember when it comes to cameras you get what you pay for. I would also go with a canon, or other name brand lens. Make sure the lense has auto focus and image stabilization. The more you zoom, the harder it is to keep the camera still and the more light you lose. I would also bet a tripod for it.
As you zoom in on your picture to bring the deer closer every little imperfection and focus points will be magnified.
I use a Canon Rebel XTI with Canon lenses (mostly 70mm-300mm) and have had good luck with it. This camera has a little different aspect ratio in the body of it, so the 70-300mm lense becomes a 400mm lense bringing your deer even closer with out the extra cost of the bigger lense. It's easy to learn the basic stuff, and as you get better with it you can switch the lense to manual focus. Good Luck