The CPU seems to have a big impact when it comes to the performance of Crysis. I have recently upgraded from a 4400+X2 2.2ghz to a Q6600 and my experience is now smoother. I'm using the same GFX card a 2900XT, but I can now push the GFX settings higher.
Your video card is a bigger problem on crysis. Any dual core can handle crysis no matter but at 1280X1024 and higher it a gpu killer. If you have an LCD running at 1680X1050 you will need the 4850 or 9800GTX+ or higher. I would only worry about the CPU if you wanted to run other things at the same time IE voice, internet, ect while playing.
I'd say you should be good to go for up to about 1680x1050 @ high settings (not very high though), assuming that's a G92 GTS. You also may have to leave physics on medium, depending on which Athlon that is.
It depends more on your video card. You will be able to play but you wont be able to put settings past medium at 1024x768. What resolution do you run ?
Is this a socket AM2?
^What eveyrone else has said thus far. Due to it being a older dual it will hold you back from being able to run it at its highest even with that nice of a GPU.