Can't ping other local Vista PC using IP

This is a strange problem. I've got 3 computers, a DSL modem and a WRT54G
wireless router. The DSL and router are bridged so everything goes through
the router. I've got a static IP with my DSL provider and everything is
configured fine in the router. All 3 PC's can surf the internet.

Each PC has it's IP static
192.168.1.2 - Main PC running Vista Ultimate with IIS 7.0 with website
192.168.1.3 - Son's laptop running Windows XP
192.168.1.4 - Other's son's PC running Vista Home Premium

Let's say my static IP is 12.12.12.12
All 3 PC's can ping this IP
I set port forwarding in the router for port 80 to point to 192.168.1.2
I entered http://12.12.12.12/index.html and it doesn't return anything.
I enabled logging in the router and can see the request.
I also used TCPView and could see the request on the PC, yet no webpage
It says SYN_SET

So I took a step back and went to kid's PCs to do the test. No luck on
either of them. And to make things even stranger
I can ping my son's 192.168.1.3 PC, but when I ping the 192.168.1.4 (Vista)
I get request timed out
Trace route shows things going fine to one PC
Other PC son's computer name and IP, but * * * for trace

And the PC I can ping, when I tried pinging my PC 192.168.1.2 from it.
REquest timeout

Linksys firewall is disabled currently
Windows Firewall is disabled also

Any help would be appreciated. This one has me baffled.

Joe P