vista firewall filter help

I know i'd probably find answer to this by googling but am in a big rush and dont have time to surf the net.

anyways, im noob to firewalls and networks. what im trying to do is make the vista firewall give access to a certain pc in the lan so that it can access the websites on the apache web server.

when the firewall is up the pc cant access the pages. but with the firewall off no porblem. I just want to giv access to 1 ip address in the network without reducing security

can anyone help?

thanx