rd ram is expensive, 256 cost me £150 for a matched pair of top quality ram. You get a boxed kit containing 2 128 pieces. rd ram has to be fitted in pairs. If you go up to 512 total this will speed up games and computer. A fx5700 ultra or 9600xt will be good for new games.
New games are stating a higher recommended system to get them at their best. Far cry's recommended specs are 3g processor, 1g of ram and 128 card. It is all up to what you can afford, I would go for adding ram first.