CoH and ultra settings

i can't have smooth gameplay with CoH in ultra settings(maxed out!). i know that my rig can handle this game with ease!
core 2 quad q9400
ati hd4870
2 gig xms2 dhx ram
1680x1050 res.

what seems to be the problem?insufficient ram?or is it my gpu?or my cpu?thanks. i have problems watching the cutscenes and sometimes it lags when i play on large maps with 8 players.thanks!

are you playing with DX10?

And make sure to defrag your harddrive or close any applications in the background.

http://www.gametrailers.com/player/20119.html