Yes... You are correct. Either card is good overall. They each have there own pros/cons... Like ATI has much more power, while nVidia has more stability (and better drivers, might I add!), etc. It is a war that will never end.
The older Radeon cards do not compare with the 6800. You are definatly right about that. But when the X800XT compares to the 6800 Ultra... I don't even have to announce the winner.
P.S.: I wouldn't really consider the Radeon 9800 (256 Mb) old... Maybe the 128 Mb... But definatly not the 256 Mb.