Hmm...I played that game on my old P4 1.6 GHz and 256 MB Ram without problems. Sure, 512 MB is recommended but 256 meets the requirements.
  I think the problem is rather with the video card that may not be supported.  
 extract forum LA site:  
 Supported Chipsets at the time of release: 
 ATI Radeon 8500/9000/9200 
 ATI Radeon 9500/9600/9700/9800 
 NVIDIA GeForce 2/3/4 family 
 NVIDIA GeForceFX family 
 Additional Chipsets supported. For a complete list of supported 3D cards, please consult the Troubleshooting guide, or visit the Technical Support section of the LucasArts Website at 
www.lucasarts.com).