Currently I am running an AMD Phenom Quad Core running at 2.2ghz, 4gb ddr2 ram, Nvidia GTS 250 vid card with 1gb ddr3 RAM overclocked from 738mhz to 795mhz. I play wow mostly in terms of gaming but I only get like 15 fps in heavily populated areas like dalaran or in raid. I know I should be getting more fps than this, I have talked to people with same vid settings and a lesser system that get higher. How can i fix this

Chowhound
Comic Vine
GameFAQs
GameSpot
Giant Bomb
TechRepublic