what's missing with this xbox basic networking set up?

[aromes]

what's missing with this xbox basic networking set up?
I am trying to connect my Xbox to a basic functional local area network (2 windows xp Pro computers + a 3COM basic ethernet hub).
On the Xbox, I went into the manual network settings and assigned
an Ip address and subnet Mask (this is a very basic setup. No need of Internet access, pppOE, Xbox live setup ... no need of gateway/dns server/...etc):
IP=192.168.1.17 (since the other 2 computers are 192.168.1.15 and 192.168.1.16) and
Subnet=255.255.255.0
I rebooted the Xbox + the 2 computers, but the 2 computers wont ping the xbox IP (keep ketting a Request time out error).
I am out of solution since:
(1)The 2 windows XP Pro have no Firewall blocking IP traffic to trhe Xbox
(2)The ethernet cable that connects the Xbox to the 3 COM standard 8 ports hub is functional (I tried successfully with the other pcs) and you can actually see on the hub the light confirming that the hub sees a connection coming from that Xbox.
(3)There's no issue with the hub's port where the Xbox is plugged to.
(4)What I did matches perfectly what I see in several documentations I found on the Net regarding this setup..but it wont work in my case.
Thanks for your help.

[xuphorz]

hmmm

this is weird.
whenever you turn on your xbox when it's plugged into the router, does it say in the lower right corner
"IP: 192.168.1.17 STATIC
Users: 0"
?