OK, so far so good, now we need more.

What can you ping?
127.0.01 ? (This is the localhost and is listed in the "hosts" table in /etc).
192.168.1.1 or Your Gateway addy if that isn't it.
Can you ping the WAN side of your router?
Can you ping Yahoo.com? (They return UDP packets, so you always should get a
return).
Can you ping some of your comuters and not others?

Let us know,,,,,

Sidebar:
When working with UNIX/Linux systems I find it really valuable to use the
"hosts" table as a documentation tool for the network.

Example:
127.0.0.1 localhost (this should ALWAYS be in the table)
192.168.1.1 Gateway GW (Doing this allows you to ping using the command
"ping GW" or "ping Gateway").
192.168.254 Printer1 NP1 (Doing this allows you to ping using the command
"ping NP1" or "ping Printer1").

Basically, everything with a static LAN address should be listed. Then you
should list your DHCP range in comments. This will tell anyone working on the
system what the network looks like. Then you can FTP it to your Winbloz servers
and PC's. Then no matter where you are standing in the network you're IP
Aliases will always work.