hiya. first i wanted to ask how much did you pay for the 9400gt? If you coudl still take it back heres a budget card thats MUCH better. i had this card while waiting for my old video card and it ran all the games i threw at it at the highest settings and its a REALLY good over clocker and stays cool when its oced high! http://www.newegg.com/Product/Product.aspx?Item=N82E16814102875&cm_re=ati_5570_low_profile-_-14-102-875-_-Product
As for your ran i guess another DDR2 1 gig would make your computer evenly balanced. i would say buy 2-3gb more if u had a better graphic card. but 1 more gig would make everything balenced. and as for prices newegg.com has r eally good deals!. i've made gaming computers for 300$ from new egg deals :) -- 9xx SOLDIERS SANS FRONTIERS
