I can't disagree with the OP that RO is a little more cpu hungry then it can be...
But a 2.4Ghz Dual core... it's getting old.
Your other more modern games, are also struggling... but I will give it to you that their medium low looks and runs better than ro2.
Buddy of mine had a Core2 E8400 and a GTS450
Runs BF3 ok, Ran RO pretty poorly.
I upgraded him for pnuts to a Phenom965 and an AM2+ mobo
Now it runs perfectly on default high.
You don't need to spend 500$
http://www.newegg.ca/Product/Product.aspx?Item=N82E16819103995
140$ (Phenom Quad Core, overclocks real easy, possible to turn to 6cores)
http://www.newegg.ca/Product/Product.aspx?Item=N82E16813186189
50$ (Cheep mobo)
http://www.newegg.ca/Product/ProductList.aspx?Submit=ENE&N=100007610%2050001183%204025%20600006126&IsNodeId=1&name=DDR3%201333%20%28PC3%2010600%29
42$ (8gigs of ram)
You can easily go to local sites and get used parts like an AM2+ mobo to save on your ram...
Best bang for your buck ! RO2 approved.
I gave my 965 to my buddy to get the 960T running it at 3.6 quad. (it runs at X6 3.6ghz but using 168Watts) I wont risk the hardware.