Why can't I play Crysis well?

I'm confused at why my PC isn't running Crysis well. I have the setting at optimal, which is medium at 1074 x 768. My gpu is a 240gt which is comparable to a 9600gt and that is supposed to run Crysis at around 60+ at those settings. I am currently getting 25 fps and when large firefights occur, 15 fps. The game also stutters and the sound makes cracking noises. I have no AA on, motion blur off, and sound quality low. Lowering the graphics doesn't seem to improve the crackling much, and I don't feel like playing on low settings. Also, I have the latest patches for Crysis installed.

Anyone have an idea what is wrong? Is my processor not cut out for the game?

If I increase the resolution to 1280 x 1024 and place the settings on high (except for shader quality) I get about 3 less fps only.



Specs:

GPU: 240 GT (512mb DDR5 memory)

4 gb ram ddr2

AMD Athlon X2 4600+ (2.4 duo)

500gb 7200rpm HD (only 40gb used, 0% frag)



I can run other games like HL2: Ep2 on the highest settings with 4x AA and 16x AF with 120fps constantly, never dropping below 60fps in the most intense explosions and firefights.Why can't I play Crysis well?
there's nothing wrong with your system. Quite frankly, Crysis needs at least a 8800gt or 9800gt or ATI equivalent (4830/4850) to play well on medium settings. As well, you should try overclocking that 4600+ to at least 2.8/2.9