Couple quick things to check:
1. Can you ping a name from command prompt? i.e ping
www.yahoo.com
If this DOES NOT work then you have a DNS problem.
2. Check Netscape settings. Make sure NEtscape isn't trying to use a Proxy
3. Verify network settings. This really only applies if you have a static IP. If you do then you probably want to verify your gateway and dns servers(see above) as well. If you use DHCP then run ifconfig and verify you are receiveing the necessary information.