photographing with a D60 since over 1 year I first used the same lens like you.
I was not very satisfied because it was vigneting (dark edges) at 300mm.
Now I use a 100-400 IS
(a really not cheap lens) but the results are quite good.A alternate to this lens will be the 75-300 IS
which a friend of mine is using.It produces a good quality.But reworking with a Photo editing program (i.e.Photoshop) is always necessary.