Crysis will no doubt be a fairly demanding game. It will require a good system to perform well. However, CryEngine2 is very scalable so lower end machines will still stand a chance.
Here is a list of confirmed information...
Crysis will run on both DX9 & DX10 as well as Windows XP and Windows Vista.
A graphics card that supports Shader Model 2 or higher is required.
CryEngine2 is estimated to scale back 2 years, and scale ahead 1.5 years.
A single 7800GTX will run the game quite well on fairly high settings according to Crysis Art Director, Michael Khaimzon.
Crysis will dynamically utilize all processing threads available. Meaning quad-core processors will be supported.
The following specs are estimates made by myself based on the above mentioned information and other sources. These estimates are NOT official - but are based on official information.
Minimum Requirements
CPU - Athlon 64 3000+/Intel 2.8 Ghz
Video - Nvidia 6200 or Ati X1300 - Shader Model 2.0
RAM - 768 MB on Windows XP or 1 GB on Windows Vista
HDD - 6 GB
Internet - 256k+
Optical Drive - DVD
Software - Direct X 9.0c with Windows XP
Recommended Requirements
CPU - Dual Core CPU - Either Athlon X2 or Intel Pentium D
Video - Nvidia 7600GT or ATI X1800GTO - Shader Model 3.0 or DX10 Equivalent
RAM - 1.5GB+
HDD - 6GB
Internet - 512k+ - 128k Upstream
Optical Drive - DVD
Software - Direct X 9.0c with Windows XP
Once again, these are estimates only and are no way official. I just want to makesure that is clear. However, if you have a graphics card similiar in performance to, or better than a 7800GTX, then expect to play Crysis quite nicely ( presuming your other system specs are up to scratch ).
Crysis System Requirements