HELP WITH UBUNTU PLZ

so, i have my machine with one HDD with winXP
and one with Ubuntu
my internet (plugged directly into modem) wont work on ubuntu
help?

>>1
Configure following files:
/etc/resolv.conf
/etc/network/interfaces

Then do one (as number: "1") of the following:
1. reboot
2. as root:
ifconfig eth0 down
ifconfig eth0 up
route add default gw <router-IP>