limited or no connectivity

I have 2 network cards in my pc. one connects to my router for internet and the other to my laptop. I’m sharing an internet connection with my laptop. I have specified an ip address on my pc and my laptop is set to automatically assign. i’m getting an error”limited or no connectivity” on my laptop. i tried connecting another pc and still get the same error.I think my pc is not assigning a correct ip for the pc’s.is there something i can u se to fix? I have XP pro and i got sp2.