Do you have vista 64 bit or vista 32 bit?
Command and conquer does not work on vista 64 bit as far as I know. And most drivers will not work unless digitally signed. I made that mistake when I purchased Vista Home Premium 64 bit OEM.
If you have 32 bit installed, try to run C&C from a different compatibility mode. This would be right clicking the icon > Properties > run in compatibility mode > And choose Windows XP or 98.
Hope this helps