install ubuntu 9.10.... and it will detect hardware & configure automatically....
anyway you can open ubuntu help file.... System > help and support > go though internet and networks > and do configuration for wired (LAN)...... para 2.1 in ubuntu 9.10
or if you can configure then follow the procedure
System > Administration > Preferences > network connections >
under wired tab .... it should have auto eth0
connection name auto eth o edit the configuration
tick the check box connect automatically
MAc address: it is assigned automatically
MTU: Automatic
IPV4 :Select Automatic (DHCP)
Apply and close the window
just reboot and see your net is working