First establish if you have a route to the big bad world:
ping 184.108.40.206 (www.sf.net
If you don't have a route to the world, check your routing table:
If there is no default gateway, then add one:
route add default gw your.gateway.ip.address
If pin does work by IP then check name resolution:
If that fails, check your DNS entries:
If there are no entries, you need to put some in.
In general you only have these problems if an IP is statically declared on your interface. If DHCP is used instead, the route and DNS entries are usually set during DHCP negotiations, even if you are assigned a fixed IP by DHCP.
If you can manually configure things, I have no idea how you make any changes stick in PCLinuxOS since I've never used it.