For those of you dealing with the wait for the June 22nd release of Battlefield 2 by spending untold hours with the recently released demo, you might want to take a look at this BF2 Demo Tweak Guide to help your system’s performance.
And for owners of Geforce 4 cards, which the demo officially does not support, you might be interested in this forum discussion on some successful techniques employed to get the game running on those video cards.