hmm , you want dual core , i dont game myself , but i have heard a few people say that for bf2 a lot of ram i required so i would go with say 2gig's o ram and
maybe an intel core 2 duo e6400 or even an e6600 the e6600 is about $320 and the e6400 is $220
the difference between them is that the e6400 has 2m shared l2 cache yet teh e6600 has 4mb shared