So after doing some monitoring and testing along with a friend of mine, we've determined that BF2 will eat up about as much RAM as you can throw at it.
I started to notice it when I was lagging behind him in terms of loading maps and getting into servers. I have a hotter (performance-wise) machine than him except for the fact that he had 2GB of RAM, and I only had 1GB.
Since then I've upgraded to 2 and it's been running a lot better... despite that, he said he was monitoring his the other nite and the game alone was eating up 1.5Gb+ of RAM. INSANE. He said it spiked higher than that at times too.
Add to this that we both have 256MB video cards and you can tell that this game is a goddamn resource hog like no other.