Yes there is a difference. If you take a look at the first comparitve picture for example, pay attention to the stone objects on the left side. There you will see the difference.
Indeed. Only difference (visible) is slightly sharper and less smudged textures.
If it runs that slow on a 4870 at 1680x1050 I had to see it on my 8800GTX... damn the 8800GTX is slowly dying
I think the 8800GTX is still going strong. Unless of course if you play with AA and really high res. But, like you said, it's one of the best GPU investments ever. On my 9800XT i could play for 3 years almost max everything, and even now it can hold a bit (only overheating issue though :/).