COD running slow for unknown reason

Well i have "acquired" Call Of Duty 4, I've set it to optimal settings and it runs very slow, I dont know how to get an exact read but im gonna estimate the FPS is like 15Any help?

I can simply guess your computer just can't run it.What are your specs?

Monile Intel Core i5-430M Provessor (2.26/2.53GHz, 1066MHz FSB, 3MB L2 cache)Windows 7Storage 640GB 5400rpm 2.5 SATAMemory 4GB DDr2 (2GB+2GB) (800MHz)
13.3" Widescreen XGA TFT Active Matrix 200NIT CSV (1366x768) resolutionGraphics ATI M92XTX 512MB (ATI Mobility Radeon HD 5145)

2.5Ghz is a bit on the slow side these days.