problem connecting 3 pcs

[burnout]

i have had my pc networked with my son's for a while now with no problems, but now i;ve decided to add my daughter's aswell. this is how they're wired up

pc 1 - network card with ip address 192.168.0.1

pc2 1st network card connected to pc1 ip address 192.168.0.2
2nd network card connected to pc 3 ip address 192.168.0.3


pc 3 network card with ip address 192.168.0.4

i can connect pc1 to pc2 and pc2 to pc3, but can't connect pc1 to pc3

does this make any sence?

(pc1) (pc2) (pc3)
192.168.0.1-------------192.168.0.2
192.168.0.3------------------------192.168.0.4


or does this explain it better? neway can some1 please tell me how i can connect pcs 1 &3 ?
thanx for reading

burnout