Oh, I would pretty much say that they will. The 7800 series has been out for what now a few months? ATI had a fair amount of time to Benchmark the 7800 series and analyse the 7800's performance verse their new cards.
You think ATI doesn't have Hundreds of Nvidia cards in their R&D department tearing them apart and benchmarking the crap out of them in comparison to theirs???
Then tweak and tune their cards to out perform the competition...
pffff.... no they aren't doing that....
Corporate America... Gotta love it...