Open a terminal and type "ifconfig" and see if you have an IP, should look something like:
Code:
eth0      Link encap:Ethernet  HWaddr 00:05:5D:48:1F:A9
          inet addr:192.168.2.166  Bcast:192.168.2.255  Mask:255.255.255.0
          inet6 addr: fe80::205:5dff:fe48:1fa9/64 Scope:Link
          UP BROADCAST RUNNING MULTICAST  MTU:1500  Metric:1
          RX packets:101878 errors:0 dropped:0 overruns:0 frame:0
          TX packets:89181 errors:0 dropped:0 overruns:0 carrier:0
          collisions:0 txqueuelen:1000
          RX bytes:111554421 (106.3 MiB)  TX bytes:9249597 (8.8 MiB)
          Interrupt:9 Base address:0x8000

lo        Link encap:Local Loopback
          inet addr:127.0.0.1  Mask:255.0.0.0
          inet6 addr: ::1/128 Scope:Host
          UP LOOPBACK RUNNING  MTU:16436  Metric:1
          RX packets:28 errors:0 dropped:0 overruns:0 frame:0
          TX packets:28 errors:0 dropped:0 overruns:0 carrier:0
          collisions:0 txqueuelen:0
          RX bytes:1400 (1.3 KiB)  TX bytes:1400 (1.3 KiB)
If you have no IP for eth0 try "sudo netcardconfig" or "sudo ifup eth0" and "sudo pump -i eth0"