Ok, im not sure how much you know about pc's and routers and stuff so lets start at the beginning.
On your pc in your network setting you should either have static settings or setting set by "dhcp"
When you goto "status" of you lan you should see,
The default gateway and dns entries should be the same ip address of your router, generally 192.168.*.* or 10.10.0.*
If thats set then log on to your router and check the ip address of the wan/pppoe session, its probly something like 196.54.*.* or 41.*.*.*.
If thats there too then open up a cmd prompt and type "ping google.com"
This will tell us if "some" traffic is working
E:\Documents and Settings\****ter>ping google.com
Pinging google.com [165.165.38.147] with 32 bytes of data:
Reply from 165.165.38.147: bytes=32 time=19ms TTL=61
Reply from 165.165.38.147: bytes=32 time=19ms TTL=61
Reply from 165.165.38.147: bytes=32 time=19ms TTL=61
Reply from 165.165.38.147: bytes=32 time=19ms TTL=61
Ping statistics for 165.165.38.147:
Packets: Sent = 4, Received = 4, Lost = 0 (0% loss),
Approximate round trip times in milli-seconds:
Minimum = 19ms, Maximum = 19ms, Average = 19ms
thats a good response,
if your dns isnt working you will get a response like
E:\Documents and Settings\****ter>ping cnn.com
Ping request could not find host cnn.com. Please check the name and try again.
if that happens try just ping an ip address
E:\Documents and Settings\****ter>ping 165.165.38.147
Pinging 165.165.38.147 with 32 bytes of data:
Reply from 165.165.38.147: bytes=32 time=21ms TTL=61
Reply from 165.165.38.147: bytes=32 time=19ms TTL=61
Reply from 165.165.38.147: bytes=32 time=19ms TTL=61
Reply from 165.165.38.147: bytes=32 time=20ms TTL=61
Ping statistics for 165.165.38.147:
Packets: Sent = 4, Received = 4, Lost = 0 (0% loss)
Approximate round trip times in milli-seconds:
Minimum = 19ms, Maximum = 21ms, Average = 19ms
if that then works then your dns is the issue, if that doesnt work then there's a bigger issue
then try do a trace route
E:\Documents and Settings\****ter>tracert 165.165.38.147
Tracing route to 165.165.38.147 over a maximum of 30 hops
1 <1 ms <1 ms <1 ms 192.168.2.4
2 18 ms 18 ms 18 ms reff-ip-lar-1-gig-3-0-0.telkom-ipnet.co.za [196.
43.11.100]
3 19 ms 19 ms 20 ms 196.43.26.106
4 20 ms 18 ms 20 ms 165.165.38.147
that shows your "hops" along, as you can see the first hop is my router 192.168.2.4, so we can tell my pc is at least routing internet traffic to the router, if it hops on from that then data is coming in from the internet.
give that a shot and tell us how it helps