I am using the Nikon D40 camera with the 300mm VR lens also. I have found that is good for about 80 yards or so without having to crop a whole lot. This would be a good start for you. Keep it clean an in a protected case when not in use.
http://www.adorama.com/NK70300AFVRU.html?searchinfo=nikon%20vr%20lens& ;item_no=13