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Can you ping back and forth between your windows hosts and the Linux host.
Look at your /etc/resolv.conf file. Are your ISP's nameservers listed?
Does filesharing work or ssh work with the linux boxes?
Are you using wireless at home? Did you change the PSK in the router?
Look at the output of "ifconfig" and the "route" commands. Is your IP in the same subnet as your router? Is the router's IP listed as the default gateway?
Try the host command, as in "host www.linuxquestions.org" to check dns.
Check the "host.conf" file. Does it contain
order hosts, bind
# The following options are used by the resolver library:
Check the /etc/nsswitch.conf file.
hosts: files mdns4_minimal [NOTFOUND=return] dns
networks: files dns
These two lines are important. The hosts: line should correspond with the host.conf line.